Chapter Four · failure evidence
What Transgenic & Recombinant Expression got wrong, from 44 dissertations
The records describe common technical obstacles encountered during recombinant protein expression and purification across diverse bacterial, insect, and mammalian host systems. Investigators frequently faced issues including insoluble inclusion body formation, complete failure of constructs to express, host cell toxicity, persistent co-purification of contaminants, and instability or misfolding in non-native hosts. These records come from PhD theses at 18 institutions, 2021 to 2026. Each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.
Expressed recombinant proteins aggregate into insoluble inclusion bodies or precipitates
Recombinant targets across plant, mammalian, bacterial, and viral origins consistently formed insoluble aggregates or partitioned into inclusion bodies upon expression or cell lysis. Modifying expression conditions with solubility tags, reduced induction temperatures, truncation variants, or alternative culture systems failed to prevent aggregation or recover soluble product.
Tried and failed
native recombinant protein expression with solubility tags applied to truncated plant protein domains. Reason: expressed proteins formed insoluble inclusion bodies rather than soluble native protein
Tried and failed
recombinant bacterial expression with affinity chromatography applied to bacterial outer membrane proteins. Reason: protein aggregated into insoluble inclusion bodies and failed affinity column binding
The interaction of glycosylated major outer membrane protein of Campylobacter jejuni with natural and synthetic ligands · University of Nottingham Repository
Tried and failed
recombinant protein expression and purification applied to bacterial effector protein. Reason: protein failed to express in soluble form under standard conditions
Antimicrobial Dynamics of the Vibrio cholerae Type VI Secretion System · Georgia Tech
Tried and failed
low-temperature low-inducer bacterial expression applied to insoluble recombinant multi-domain human proteins. Reason: protein remained completely partitioned into insoluble inclusion bodies despite reduced expression kinetics
Establishing The Foundations For Biophysical Studies Of Allostery In Parkin E3 Ubiquitin Ligase · Penn
Tried and failed
vesicle nucleating peptide tagging for protein secretion applied to recombinant fusion protein expression. Reason: failed to export vesicles and resulted exclusively in insoluble protein aggregation
Tried and failed
recombinant protein expression and solubilization applied to heterologous full-length eukaryotic protein. Reason: insoluble protein aggregation in bacterial pellets
Investigating the Role of Drosophila Tomosyn in Synaptic Strength and Plasticity · MIT
Tried and failed
recombinant protein expression in bacterial and insect hosts applied to full-length multidomain E3 ligases. Reason: constructs formed insoluble aggregates in both bacterial and insect cell expression systems
Structural and functional characterisation of Class IV TRIM E3 ligases · Imperial
Lost to a baseline
NoCAR recombinant expression in OMW produced 146.24 µg/mL insoluble inclusion bodies (122.5% higher than shake flasks at 65.73 µg/mL) and 19.29% lower soluble yield, attributed to temperature gradients during shaking incubation.
Validierung von 3D-gedruckten Reaktorsystemen für biotechnologische Applikationen · Leibniz Universität Hannover Repository
Considered and rejected
Considered and rejected: Rejected recombinant expression of MOMP in E. coli due to inclusion body formation and poor His-tag binding, opting for native extraction directly from C. jejuni.
The interaction of glycosylated major outer membrane protein of Campylobacter jejuni with natural and synthetic ligands · University of Nottingham Repository
Considered and rejected
Considered and rejected: Excluded recombinant proteins EscF, EspF, and AnsB from the initial in vitro DNA digestion screening because they were either not expressed or formed insoluble inclusion bodies in E. coli BL21(DE3).
THE ROLE OF ATTACHING AND EFFACING PATHOGENS IN PROMOTING LETHAL DIARRHEA AND LONG-TERM COLON TUMORIGENESIS · JScholarship
Tried and failed
recombinant bacterial protein expression applied to full-length viral coat protein. Reason: expressed protein formed insoluble aggregates upon cell lysis
THE MASTER MANIPULATOR; CRYSTAL CLEAR PERSPECTIVES ON VIRAL INFECTIVITY · Cornell
Tried and failed
recombinant expression in bacterial and insect systems applied to full-length eukaryotic multidomain protein. Reason: expressed protein formed insoluble aggregates and underwent extensive proteolysis
Structural and biochemical studies of RAD51 filament modulators · Imperial
Tried and failed
recombinant bacterial expression with fusion tags and truncations applied to membrane-associated protein. Reason: protein remained completely insoluble across multiple expression vectors, buffer conditions, and N-terminal transmembrane truncations
A small molecule-guided structure-function exploration of mitochondrial aldehyde dehydrogenase · MIT
Construct modifications and heterologous systems result in complete expression failure or negligible yields
Multiple multi-protein complexes, eukaryotic transcription factors, and engineered protein variants completely failed to express or could not be recovered across various host systems. Specific sequence alterations such as framework backmutations, deletion of terminal cap domains, or engineered disulfide pairings severely reduced yields or abrogated recombinant expression entirely.
Tried and failed
recombinant protein complex expression and affinity purification applied to heterodimeric protein complex in mammalian cells. Reason: complex could not be expressed and purified despite multiple tagged constructs
AMPK and FLCN/FNIP: investigating regulation, interactions and signalling crosstalk · Imperial
Tried and failed
recombinant operon co-expression and affinity purification applied to bacterial defense multi-protein complexes. Reason: proteins failed to express or purify from heterologous bacterial host
Supramolecular complex formation in bacterial anti-phage defense and viral immune evasion · Harvard
Tried and failed
recombinant fusion protein expression with unnatural residues applied to cyclic depsipeptide synthesis. Reason: fusion proteins failed to express or target peptides could not be extracted from cell lysate
Genetically programmed cell-based synthesis of non-natural peptide and depsipeptide macrocycles. · Cambridge
Tried and failed
recombinant protein expression and purification applied to full-length lipid-binding protein and isolated domains. Reason: unable to successfully purify the isolated C-terminal domains or full-length protein for in vitro analysis
Tried and failed
recombinant protein expression in bacterial host applied to heterologous eukaryotic transcription factors. Reason: complete lack of protein expression across multiple construct designs and growth conditions
Tried and failed
baculovirus-mediated recombinant protein expression applied to heterodimeric protein complexes. Reason: expression of the protein complexes in insect cells was unsuccessful
Considered and rejected
Considered and rejected: Rejected expressing OaAEP1 completely without its C-cap because recombinant expression was unsuccessful.
Considered and rejected
Considered and rejected: Rejected combining multiple engineered disulfide bonds or pairing S884C/A893C with proline substitution F817P due to reduced recombinant expression yields
Targeting viral fusion for immunity and therapeutics against infection · UT Austin
Tried and failed
framework backmutation during antibody humanisation applied to humanised Fab fragment expression. Reason: a specific framework backmutation abrogated recombinant protein expression completely
Recombinant products co-purify with persistent host contaminants and cellular chaperones
Purification protocols failed to separate target recombinant proteins from endogenous host cell components including membrane transporters, nucleic acids, and chaperone proteins. In other cases, expression in bacterial systems caused persistent endotoxin contamination exceeding regulatory thresholds or chromatography steps lacked sufficient resolving power to isolate modified targets.
Tried and failed
inclusion body prep with ion exchange chromatography applied to multiply modified recombinant proteins. Reason: standard chromatography steps lacked sufficient resolving power to yield pure modified target protein
Tried and failed
recombinant protein expression without cognate binding partner applied to heterologous reverse transcriptase purification. Reason: produced very low yield and copurified with host chaperone proteins due to misfolding
Characterizing retron Efe1 reverse transcriptase interactions with ncRNA · UT Austin
Considered and rejected
Considered and rejected: Rejected using bacterial recombinant expression for in vivo affibody applications due to persistent endotoxin contamination above FDA device limits, switching to solid-phase peptide synthesis (SPPS).
Engineering Shelf-Stable Affibody-Functionalized Hydrogels for Controlled Dual Release of Bone Morphogenetic Protein-2 and Interleukin-4 · Scholars' Bank
Considered and rejected
Considered and rejected: Purification of recombinant RTP4 N-terminal ZFD directly from bacteria without denaturing/refolding failed because it co-purified with bacterial nucleic acids and formed insoluble aggregates.
Identification of Receptor Transporting Proteins As Conserved Antiviral Effectors in Vertebrates · DSpace at UTSWMED
Tried and failed
recombinant protein expression in wild-type host applied to membrane protein purification. Reason: endogenous host membrane transporter co-purified persistently despite high-stringency affinity washes
Recombinant protein expression causes host toxicity and impaired cellular growth
Heterologous expression of toxic regulatory factors and structural proteins caused host cell toxicity, transformation failure, and significantly reduced culture biomass relative to parent strains. Media supplementation strategies also failed to rescue host cell viability or restore proper membrane trafficking.
Tried and failed
recombinant bacterial protein expression and inclusion refolding applied to large parasite structural protein domain. Reason: host cell toxicity upon induction, inclusion body formation, and failed in vitro refolding despite solubility tags
Structural biology of T. gondii glideosome-associated Connector (TgGAC) · Imperial
Considered and rejected
Considered and rejected: Excising and ligating the G-418 resistance gene into host Bodo sp. DNA was abandoned in favor of intact undigested plasmid because recombinant experiments yielded inferior growth and unproven insertion.
Genetic Transformation in an Axenically Cultured Protozoan (Bodo sp.) · TXST Digital Repository
Lost to a baseline
Biomass yield of recombinant strain rSZ No. 8 at 120 h (27.81 ± 1.75 g/L) was significantly lower than the parent strain B3 (31.36 ± 1.57 g/L, P < 0.05).
Schizochytrium microalgae expressing recombinant bovine lactoferrin as a route to improve intestinal health in calves · Research Repository UCD
Tried and failed
heme precursor supplementation in culture media applied to membrane protein expression and cell viability. Reason: failed to improve host cell health or recombinant protein membrane trafficking
The Development Of Novel Genetically Encoded Voltage Indicators Using De Novo Designed Proteins · Penn
Tried and failed
co-expressing recombinant single-stranded DNA binding proteins applied to heterologous bacterial recombineering. Reason: heterologous single-stranded DNA binding protein expression caused severe host toxicity and transformation failure
Purified recombinant proteins suffer from structural instability and uncontrolled aggregation
Several purified proteins exhibited irreversible aggregation, high polydispersity, or conformational heterogeneity in their isolated states. In other instances, tag-mediated assembly produced inconsistent structural packing that yielded mismatched solid-state spectra.
Tried and failed
recombinant protein expression and truncation constructs applied to large membrane-associated bacterial adhesin protease. Outcome: unstable. Reason: both full-length and truncated constructs suffered irreversible aggregation upon purification
Tried and failed
recombinant protein expression with fusion tag applied to amyloid fibril preparation. Reason: yielded inconsistent fibril assembly resulting in mismatched solid-state NMR spectra
Structural Characterization of Plaque Seeded Amyloid-β Fibrils by Magic Angle Spinning NMR · MIT
Tried and failed
recombinant purification of full-length coiled-coil protein applied to bacterial cell wall regulatory proteins. Outcome: unstable. Reason: the coiled-coil region caused polydispersity and aggregation in the apo state
Unifying regulatory mechanism of bacterial cell wall synthesis · Harvard
Heterologous hosts lack the biochemical machinery required for native modifications and assembly
Recombinant expression in bacterial hosts failed when targets required mammalian-specific post-translational modifications like N-glycosylation and disulfide bond formation to fold properly. Similarly, non-native hosts failed to support extracellular crystal assembly or lacked specialized chemical features such as cleavable disulfide linkers.
Tried and failed
recombinant fusion protein crystal encapsulation applied to heterologous spore-forming bacterial expression systems. Outcome: did not generalise. Reason: fusion proteins failed to form extracellular crystals when expressed in non-native bacterial host strains
Spore-forming bacteria as pharmaceutical factories · Cambridge
Tried and failed
Bacterial expression of complex mammalian lectins applied to recombinant protein production. Reason: Lack of N-glycosylation and disulfide bond formation caused misfolding and non-specific binding.
Carbohydrate and bacterial binding specificity of human intelectin-1 · MIT
Considered and rejected
Considered and rejected: Rejected recombinant expression of biotinylated antigen because recombinant biotinylation lacks the cleavable disulfide linker required for rapid low-pH antigen release.
Investigating mechanisms of neutralization of staph enterotoxin B · ResearchWorks
Left open by the authors
Problems the authors named and did not get to.
Left open
Perform structural and functional analyses to verify the integrity of recombinant HAP40 purified from E. coli inclusion bodies. Blocker: Requires a wet biology lab and physical protein samples purified from bacterial inclusion bodies
Left open
Recombinantly generate and express the identified surface-accessible EV protein candidates in a biological expression system. Blocker: Requires a wet laboratory for molecular cloning, recombinant protein expression, and cell culture
Identification of surface accessible proteins in parasitic nematode extracellular vesicles · Iowa State
Left open
Recombinantly express and functionally validate plasma monoclonal antibodies from lineages exclusively detected in IC-Seq to identify effector functions. Blocker: Requires wet-lab facilities for recombinant protein expression and functional antibody effector assays
Left open
Perform cell-free in vitro reconstitution of R-body synthesis using combinatorial expression of Reb A, B, C, and D. Blocker: Requires a wet lab, recombinant proteins/plasmids, and cell-free protein expression systems.
An Interdisciplinary Investigation of Conformational Changes in Quasi-Crystalline Protein Array R-bodies in Response to pH · ResearchWorks
Left open
Express recombinant retron in host cells lacking the endogenous Eco1 operon to prevent crosstalk. Blocker: Requires wet-lab genetic engineering, bacterial cell culture, and protein expression facilities
Characterizing retron Efe1 reverse transcriptase interactions with ncRNA · UT Austin
Left open
Encapsulate ELP-fused deoxyviolacein pathway enzymes (VioC and VioE) or membrane proteins into protein vesicles to construct artificial organelles. Blocker: Requires wet lab biochemical synthesis, recombinant fusion protein expression, and membrane protein reconstitution
Engineering fusion protein vesicles for biocatalysis and drug delivery applications · Georgia Tech
Left open
Heterologously express and assemble a functional recombinant ammonia monooxygenase (AMO) holoenzyme complex in E. coli. Blocker: Requires a wet biology lab, specialized expression vectors, bacterial culturing, and biochemical purification equipment
AN INVESTIGATION INTO COPPER PROTEINS GERMANE TO BIOLOGICAL AMMONIA OXIDATION · Cornell
Left open
Produce functional NA tetrameric head coating antigens to enhance ELISA detection breadth and preserve conformational epitopes. Blocker: Requires wet lab recombinant protein expression, purification, and biochemical validation apparatus
Left open
Characterise and compare recombinant in vitro FapC homo-amyloids with natively secreted hetero-amyloids. Blocker: Requires wet-lab biochemistry, protein expression, and structural characterization facilities.
Structural and functional insights into Functional Amyloid biogenesis in Pseudomonas · Imperial
Left open
Recombinantly express antibody 436A1 and assay its epitope specificity, parasite growth inhibition, and complement-activation potency against malaria parasites. Blocker: Requires wet-lab facilities, recombinant protein expression systems, and live malaria parasite cultures for functional biological assays.
Checking a claim in this area?
We can run the same search on any method or claim. If nothing turns up, we will say so, and that proves nothing on its own.