PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 3056926

Two cellular components, PrlA and SecB, that recognize different sequence determinants are required for efficient protein export.

N J Trun·J Stader·A Lupas·C Kumamoto·T J Silhavy
View original source ↗Export metadata ↓

Abstract

We exploited the conditional-lethal phenotype of secB null mutations to demonstrate that SecB function was required for PrlA-mediated suppression of signal sequence mutations. The results of these experiments provide information about the functions performed and the sequence determinants recognized by each of these components of the protein export machinery of Escherichia coli.

Explore related subjects

Bacterial Outer Membrane ProteinsBacterial ProteinsEscherichia coliEscherichia coli ProteinsGenesGenes, BacterialMutationPhenotypePorinsReceptors, VirusSEC Translocation ChannelsJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

N J Trun, J Stader, A Lupas, C Kumamoto, T J Silhavy. 1988. Two cellular components, PrlA and SecB, that recognize different sequence determinants are required for efficient protein export.. https://doi.org/10.1128/jb.170.12.5928-5930.1988

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2025

TamL is a Key Player of the Outer Membrane Homeostasis in Bacteroidota.

In Proteobacteria, the outer membrane protein TamA and the inner membrane-anchored protein TamB form the Translocation and Assembly Module (TAM) complex, which facilitates the transport of autotransporters, virulence factors, and likely lipids across the two membranes. In Bacteroidota, TamA is replaced by TamL, a TamA-like lipoprotein with a lipid modification at its N-terminus that likely anchors it to the outer membrane. This structural difference suggests that TamL may have a distinct function compared to TamA. However, the role of TAM in bacterial phyla other than Proteobacteria remains unexplored. Our study aimed to elucidate the function of TamL in Flavobacterium johnsoniae, an environmental Bacteroidota. Unlike its homologs in Proteobacteria, we found that TamL and TamB are essential in F. johnsoniae. Through genetic, phenotypic, proteomic, and lipidomic analyses, we show that TamL depletion severely compromises outer membrane integrity, as evidenced by reduced cell viability, altered cell shape, increased susceptibility to membrane-disrupting agents, and elevated levels of outer membrane lipoproteins. Notably, we did not observe an overall decrease in the levels of β-barrel outer membrane proteins, nor substantial alterations in outer membrane lipid composition. By pull-down assays, we found TamL co-purifying with TamB in F. johnsoniae, suggesting an interaction. Furthermore, we found that while TamL and TamB monocistronic genes are conserved among Bacteroidota, only some species encode multiple TamL, TamB and TamA proteins. To our knowledge, this study is the first to provide functional insights into a TAM subunit beyond Proteobacteria.

Bacterial Outer Membrane Proteins↗
PubMed1997

A family of gram-negative bacterial outer membrane factors that function in the export of proteins, carbohydrates, drugs and heavy metals from gram-negative bacteria.

Gram-negative bacteria have evolved transport complexes that export macromolecules and toxic substances across the two membranes of the cell envelope in a single energy coupled step. The process requires (1) a cytoplasmic membrane export system, (2) a membrane fusion protein (MFP), and (3) an outer membrane factor (OMF). Families comprising the former two constituents have been described previously. We here present an analysis of the phylogenetic and structural characteristics of the OMF family. Twenty-one members of this family have been identified, and based on available evidence, they function in conjunction with ABC, RND, MFS and/or other types of cytoplasmic transport systems. OMFs exhibit fairly uniform sizes (398-495 residues with two exceptions), and based on computational analyses, they may form beta-barrel structures consisting of up to 16 beta-strands. Phylogenetic analyses reveal that while the MFPs cluster in accordance with the type of cytoplasmic membrane transport systems with which they function, OMFs do not. We conclude that OMFs probably comprise a family of outer membrane porin-type proteins of uniform structure which did not coevolve with their cognate cytoplasmic membrane transport systems.

Bacterial Outer Membrane Proteins↗
PubMed1997

Molecular organisation of the ice nucleation protein InaV from Pseudomonas syringae.

A new ice nucleation gene from Pseudomonas syringae was isolated and overexpressed as a fully active protein in Escherichia coli in order to gain experimental data about the structure of ice nucleation proteins. No evidence of a signal sequence or secondary glycosylation was found. Differences in the extent of aggregation were shown to modulate the ice nucleation activity. The circular dichroism spectrum of the purified protein indicated the presence of beta-sheet structure. This finding supports a recently proposed hypothetical model for the structure of ice nucleation proteins, which provides a plausible explanation for their aggregation tendency.

Bacterial Outer Membrane Proteins↗