PMID:17071751

Citation	Ureta, AR, Endres, RG, Wingreen, NS and Silhavy, TJ (2007) Kinetic analysis of the assembly of the outer membrane protein LamB in Escherichia coli mutants each lacking a secretion or targeting factor in a different cellular compartment. J. Bacteriol. 189:446-54
Abstract	Outer membrane beta-barrel proteins in gram-negative bacteria, such as Escherichia coli, must be translocated from their site of synthesis in the cytoplasm to the periplasm and finally delivered to the outer membrane. At least a dozen proteins located in the cytoplasm, the periplasm, and both the inner and outer membranes are required to catalyze this complex assembly process. At normal growth temperatures and conditions the transport and assembly processes are so fast that assembly intermediates cannot be detected. Using cells grown at a low temperature to slow the assembly process and pulse-chase analysis with immunodetection methods, we followed newly synthesized LamB molecules during their transit through the cell envelope. The quality and reproducibility of the data allowed us to calculate rate constants for three different subassembly reactions. This kinetic analysis revealed that secB and secD mutants exhibit nearly identical defects in precursor translocation from the cytoplasm. However, subsequent subassembly reaction rates provided no clear evidence for an additional role for SecD in LamB assembly. Moreover, we found that surA mutants are qualitatively indistinguishable from yfgL mutants, suggesting that the products of both of these genes share a common function in the assembly process, most likely the delivery of LamB to the YaeT assembly complex in the outer membrane.
Links	PubMed PMC1797403 Online version:10.1128/JB.01103-06
Keywords	Bacterial Outer Membrane Proteins/chemistry; Bacterial Outer Membrane Proteins/genetics; Bacterial Outer Membrane Proteins/metabolism; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Carrier Proteins/chemistry; Carrier Proteins/genetics; Carrier Proteins/metabolism; Cell Membrane/metabolism; Cytoplasm/metabolism; Densitometry; Dimerization; Electrophoresis, Polyacrylamide Gel; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Gene Expression Regulation, Bacterial; Immunoprecipitation; Kinetics; Membrane Transport Proteins/chemistry; Membrane Transport Proteins/genetics; Membrane Transport Proteins/metabolism; Models, Biological; Mutation; Peptidylprolyl Isomerase/chemistry; Peptidylprolyl Isomerase/genetics; Peptidylprolyl Isomerase/metabolism; Periplasm/metabolism; Porins; Protein Folding; Protein Processing, Post-Translational; Protein Sorting Signals; Protein Transport; Receptors, Virus/chemistry; Receptors, Virus/genetics; Receptors, Virus/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOLI:SURA	involved_in	GO:0050821: protein stabilization	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
ECOLI:SURA	involved_in	GO:0051085: chaperone cofactor-dependent protein refolding	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
ECOLI:SURA	involved_in	GO:0006457: protein folding	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete

References

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