Intragenic Regions Required for LamB Export
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Escherichia coli strains containing a series of lamB-lacZ fusions have been isolated and characterized. Each of these fusions specifies a hybrid protein with LamB sequences at the NH2 terminus and a large functional COOH-terminal fragment of beta-galactosidase. The amount of LamB present in the various hybrid proteins ranges from as few as 4 amino acids to a complete signal sequence (25 amino acids) plus 49 amino acids of the mature protein. With respect to hybrid protein export these fusions fall into three classes. Hybrid proteins with an incomplete LamB signal sequence or those that have a complete signal sequence plus 27 or fewer amino acids of the mature LamB protein are not exported and remain in the cytoplasm. In contrast, fusion strains attempt to export hybrid proteins that contain a complete signal sequence plus 39 or 43 amino acids of mature LamB. However, these proteins are not localized to the outer membrane. Finally, a hybrid protein that is slightly larger, containing 49 amino acids of mature LamB, is found in the outer membrane in appreciable amounts. These fusions, together with previously described lamB-lacZ fusions, have enabled us to define more precisely the minimal amount of lamB required to initiate the process of protein export. Moreover, they genetically locate a signal that appears to guide LamB to the outer membrane. This signal is within a region of amino acid homology shared by other major outer membrane proteins [ Nikaido , H. & Wu, H. C. P. (1984) Proc. Natl. Acad. Sci. USA 81, 1048-1052].
Fisher A, Kim J, Perez-Rodriguez R, Tullman-Ercek D, Fish W, Henderson L Microb Biotechnol. 2011; 1(5):403-15.
PMID: 21261860 PMC: 3057487. DOI: 10.1111/j.1751-7915.2008.00041.x.
Activation of colicin M by the FkpA prolyl cis-trans isomerase/chaperone.
Helbig S, Patzer S, Schiene-Fischer C, Zeth K, Braun V J Biol Chem. 2010; 286(8):6280-90.
PMID: 21149455 PMC: 3057819. DOI: 10.1074/jbc.M110.165274.
Hand N, Silhavy T J Bacteriol. 2003; 185(22):6530-9.
PMID: 14594825 PMC: 262091. DOI: 10.1128/JB.185.22.6530-6539.2003.
Secretion of LamB-LacZ by the signal recognition particle pathway of Escherichia coli.
Bowers C, Lau F, Silhavy T J Bacteriol. 2003; 185(19):5697-705.
PMID: 13129940 PMC: 193965. DOI: 10.1128/JB.185.19.5697-5705.2003.
Green fluorescent protein functions as a reporter for protein localization in Escherichia coli.
Feilmeier B, Iseminger G, Schroeder D, Webber H, Phillips G J Bacteriol. 2000; 182(14):4068-76.
PMID: 10869087 PMC: 94594. DOI: 10.1128/JB.182.14.4068-4076.2000.