{"doi":"10.1128/mbio.01769-25","title":"Bypassing BamD essentiality by mutations in a non-essential substrate","abstract":"<jats:title>ABSTRACT</jats:title>\n                  <jats:sec>\n                    <jats:title/>\n                    <jats:p>\n                      The β-barrel assembly machinery (Bam) is essential for assembling all transmembrane β-barrel outer membrane proteins in gram-negative bacteria. The Bam complex consists of the central β-barrel protein BamA and accessory Bam lipoproteins, including the widely conserved and essential BamD. BamD is assumed to be an essential regulator of OMP assembly, as its absence causes a global defect in OMP biogenesis. Here, we challenge this view by demonstrating that BamD essentiality is both conditional and substrate specific. In\n                      <jats:italic toggle=\"yes\">Escherichia coli</jats:italic>\n                      , its function can be bypassed by preventing BamA jamming by a single, non-essential substrate RcsF. Our findings suggest that BamD plays two distinct roles in the Bam complex. It prevents improper RcsF engagement that can jam BamA, and it kinetically enhances BamA-mediated OMP assembly. Contrary to prevailing models, we demonstrate that the second function in general OMP assembly is not essential. We report a genetic background in which each Bam lipoprotein is dispensable for viability, providing a powerful new system for investigating their functions in OMP assembly in the context of unmodified, wild-type BamA.\n                    </jats:p>\n                    <jats:sec>\n                      <jats:title>IMPORTANCE</jats:title>\n                      <jats:p>\n                        The β-barrel assembly machinery (Bam) complex assembles all outer membrane proteins (OMPs) and is conserved and essential across all gram-negative bacteria. While BamA is critical for the folding and insertion of OMPs into the outer membrane, BamD is also considered essential for OMP assembly because its loss leads to a global reduction in OMP levels and cell death. Our results show that BamD is important but not essential for general OMP assembly. In\n                        <jats:italic toggle=\"yes\">Escherichia coli,</jats:italic>\n                        BamD’s essentiality arises from its role in preventing a single challenging substrate from jamming BamA and indirectly abolishing OMP assembly. This work challenges long-standing assumptions about BamD’s function, underscores the substrate-specific roles of accessory Bam components, and offers important new considerations for interpreting genetic studies of the Bam complex.\n                      </jats:p>\n                    </jats:sec>\n                  </jats:sec>","journal":"mBio","year":2025,"id":645928,"datarank":0.24141568686511508,"base_score":1.6094379124341003,"endowment":1.6094379124341003,"self_citation_contribution":0.24141568686511508,"citation_network_contribution":0.0,"self_endowment_contribution":0.24141568686511508,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":4,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":869629,"name":"Anna Konovalova","orcid":"0000-0002-2238-8849","position":1,"is_corresponding":false},{"id":823513,"name":"Santosh Kumar","orcid":"0000-0003-4804-5120","position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Bypassing BamD essentiality by mutations in a non-essential substrate","abstract":"<jats:title>ABSTRACT</jats:title>\n                  <jats:sec>\n                    <jats:title/>\n                    <jats:p>\n                      The β-barrel assembly machinery (Bam) is essential for assembling all transmembrane β-barrel outer membrane proteins in gram-negative bacteria. The Bam complex consists of the central β-barrel protein BamA and accessory Bam lipoproteins, including the widely conserved and essential BamD. BamD is assumed to be an essential regulator of OMP assembly, as its absence causes a global defect in OMP biogenesis. Here, we challenge this view by demonstrating that BamD essentiality is both conditional and substrate specific. In\n                      <jats:italic toggle=\"yes\">Escherichia coli</jats:italic>\n                      , its function can be bypassed by preventing BamA jamming by a single, non-essential substrate RcsF. Our findings suggest that BamD plays two distinct roles in the Bam complex. It prevents improper RcsF engagement that can jam BamA, and it kinetically enhances BamA-mediated OMP assembly. Contrary to prevailing models, we demonstrate that the second function in general OMP assembly is not essential. We report a genetic background in which each Bam lipoprotein is dispensable for viability, providing a powerful new system for investigating their functions in OMP assembly in the context of unmodified, wild-type BamA.\n                    </jats:p>\n                    <jats:sec>\n                      <jats:title>IMPORTANCE</jats:title>\n                      <jats:p>\n                        The β-barrel assembly machinery (Bam) complex assembles all outer membrane proteins (OMPs) and is conserved and essential across all gram-negative bacteria. While BamA is critical for the folding and insertion of OMPs into the outer membrane, BamD is also considered essential for OMP assembly because its loss leads to a global reduction in OMP levels and cell death. Our results show that BamD is important but not essential for general OMP assembly. In\n                        <jats:italic toggle=\"yes\">Escherichia coli,</jats:italic>\n                        BamD’s essentiality arises from its role in preventing a single challenging substrate from jamming BamA and indirectly abolishing OMP assembly. This work challenges long-standing assumptions about BamD’s function, underscores the substrate-specific roles of accessory Bam components, and offers important new considerations for interpreting genetic studies of the Bam complex.\n                      </jats:p>\n                    </jats:sec>\n                  </jats:sec>","is_dataset_classified":null,"base_score":1.6094379124341003,"endowment":1.6094379124341003,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"40823823","pmcid":"PMC12421809","openalex_id":"https://openalex.org/W4413286309","authors":[],"funders":[{"funder_name":"National Institute of General Medical Sciences","grant_id":"R01GM133904","title":null},{"funder_name":"National Institute of General Medical Sciences","grant_id":"R35GM156651","title":null},{"funder_name":"Welch Foundation","grant_id":"AU-1998-20220331","title":null}],"total_grants":3,"fwci":3.7539,"citation_percentile":0.93495991,"influential_citations":0,"citation_trend":[{"year":2025,"count":2},{"year":2026,"count":2}],"oa_status":"gold","license":"cc-by","oa_locations":[{"url":"https://doi.org/10.1128/mbio.01769-25","host_type":"journal"},{"url":"https://doi.org/10.1128/mbio.01769-25","host_type":"publisher"},{"url":"https://journals.asm.org/doi/pdf/10.1128/mbio.01769-25","host_type":"publisher"},{"url":"https://pubmed.ncbi.nlm.nih.gov/40823823","host_type":"repository"},{"url":"https://digitalcommons.library.tmc.edu/uthgsbs_docs/6004","host_type":"repository"},{"url":"https://doaj.org/article/57ce04b3b3814a4a9fbdc93c59761261","host_type":"repository"},{"url":"https://www.ncbi.nlm.nih.gov/pmc/articles/12421809","host_type":"repository"},{"url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC12421809/","host_type":"repository"},{"url":"https://digitalcommons.library.tmc.edu/context/uthgsbs_docs/article/6860/viewcontent/mbio.01769_25.pdf","host_type":"repository"},{"url":"https://europepmc.org/articles/PMC12421809","host_type":"Europe_PMC"},{"url":"https://europepmc.org/articles/PMC12421809?pdf=render","host_type":"Europe_PMC"}],"fields_of_study":["Bacterial Genetics and Biotechnology","RNA and protein synthesis mechanisms","Antibiotic Resistance in Bacteria","Escherichia coli Proteins","Bacterial Outer Membrane Proteins","Escherichia coli","Mutation","Lipoproteins"],"mesh_terms":["Bacterial Outer Membrane Proteins","Escherichia coli","Lipoproteins","Mutation","Escherichia coli Proteins"],"keywords":["Bama","Bacterial outer membrane","Biogenesis","Biology","Context (archaeology)","Inner membrane","Function (biology)","Transmembrane protein","Escherichia coli","Cell biology","Genetics","Membrane","Gene","Receptor","Protein folding","Gram-negative Bacteria","Bam Complex","Outer Membrane Biogenesis"],"sdg_mappings":[],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[{"name":"pdb"}],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-09T10:42:00.032068Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}