On protein translocation across bacterial cytoplasmic membranes

Tai, Phang C.; Lian, Jianping; Yu, Nianjun; Fandl, James P.; Xu, Haoda; Vidugirienė, Jolanta

doi:10.1007/bf00580615

Cited by 5 publications

(4 citation statements)

References 34 publications

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“…Equally remarkable is the fact that depletion studies have not demonstrated a role for Trigger Factor in the secretion and processing of any polypeptide in vivo (Guthrie and Wickner, 1990), despite the fact that it was originally identified as a chaperone essential for the translocation of a protein into isolated membrane vesicles in vitro (Crooke and Wickner, 1987; Crooke et al ., 1988). Depletion of Trigger Factor does cause E.coli to loose viability at a faster rate at 4°C (Kandror et al ., 1997), and overexpression causes an increase in filamentation in growing cultures of E.coli (Guthrie and Wickner, 1990; Tai et al ., 1992). However, while these latter studies have suggested that Trigger Factor is important, the physiological function of Trigger Factor has remained an enigma.…”

Section: Discussionmentioning

confidence: 99%

A role for Trigger Factor and an Rgg-like regulator in the transcription, secretion and processing of the cysteine proteinase ofStreptococcus pyogenes

1998

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The ability of numerous microorganisms to cause disease relies upon the highly regulated expression of secreted proteinases. In this study, mutagenesis with a novel derivative of Tn4001 was used to identify genes required for the expression of the secreted cysteine proteinase (SCP) of the pathogenic Gram-positive bacterium Streptococcus pyogenes. Designated as Rop loci (regulation of proteinase), ropB is a rgg-like transcriptional activator required for transcription of the gene which encodes the proteinase. In contrast, ropA contributes post-transcriptionally to the secretion and processing of SCP and encodes a homologue of Trigger Factor, a peptidyl-prolyl isomerase and putative chaparone which is highly conserved in most bacterial species, but of unknown function. Analysis of additional ropA mutants demonstrated that RopA acts both to assist in targeting SCP to the secretory pathway and to promote the ability of the proprotein to establish an active conformation upon secretion. This latter function was dependent upon the peptidyl-prolyl isomerase domain of RopA and mutants that lacked this domain exhibited a bipartite deficiency manifested as a kinetic defect in autologous processing of the proprotein to the mature proteinase, and as a catalytic defect in the mature proteinase. These results provide insight into the function of Trigger Factor, the regulation of proteinase activity and the mechanism of secretion in Gram-positive bacteria.

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Section: Discussionmentioning

confidence: 99%

A role for Trigger Factor and an Rgg-like regulator in the transcription, secretion and processing of the cysteine proteinase ofStreptococcus pyogenes

1998

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“…Therefore, SecA on the membranes may play a structural role as well as a catalytic role for protein translocation across the inner membrane. The structural role of the SecA may also provide an explanation for the findings that SecY-deficient membranes and SecE-deficient membranes are active in protein translocation in vitro (14,50,51). 4,5 Watanabe and Blobel (14) have reported that the urea-or heparin-extracted membrane vesicles, which contained only membrane-integral SecA, were fully active in protein translocation in the presence of F 1 -ATPase.…”

Section: A 48-kda Domain Is Constantly Embedded In the Membrane Regarmentioning

confidence: 99%

A Significant Fraction of Functional SecA Is Permanently Embedded in the Membrane

Chen

Tai

1996

Journal of Biological Chemistry

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SecA has been suggested to cycle on and off the cytoplasmic membrane of Escherichia coli during protein translocation. We have reconstituted 35 S-SecA onto SecA-depleted membrane vesicles and followed the fate of the membrane-associated 35 S-SecA during protein translocation. Some 35 S-SecA was released from the membranes in a translocation-independent manner. However, a significant fraction of 35 S-SecA remained on the membranes even after incubation with excess SecA. This fraction of 35 S-SecA was shown to be integrated into the membrane and was active in protein translocation, indicating that SecA cycling on and off membrane is not required for protein translocation. Proteolysis experiments did not support the model of SecA insertion and deinsertion during protein translocation; instead, a major 48-kDa domain was found persistently embedded in the membrane regardless of translocation status. Thus, in addition to catalyzing ATP hydrolysis, certain domains of SecA probably play an important structural role in the translocation machinery, perhaps forming part of the protein-conducting channels.

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“…Campylobacters have been observed to adopt filamentous forms on transition from exponential to stationary phase (Griffiths, 1993), implying that certain cell division genes are affected by growth phase. In addition, Tai et al (1992) reported that levels of the protein encoded by seel (tig) increased on entry to stationary phase in E. coli.…”

Section: Resultsmentioning

confidence: 99%

“…Similarly overexpression of the Campylobacter tig gene also leads to the filamentation of E. coli cells. It has also been proposed that the product of the tig gene (described as Seel), has a regulatory function in protein translocation across bacterial cytoplasmic membranes (Tai et al, 1992). The precise physiological function of this essential gene product remains obscure.…”

Section: Discussionmentioning

confidence: 99%

The gene for Campylobacter trigger factor: evidence for multiple transcription start sites and protein products

1995

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A gene encoding a protein of apparent molecular mass 56 kDa that shares 31 O/ O identity with the amino acid sequence of trigger factor from Escherichia coli (a protein thought to be involved in cell division), was cloned from Campylobacter jejuni NCTC 11 168. The clone was selected from a lambda ZAP II genomic DNA library following an immunoacreen using antiserum raised against glycine-extractable proteins from C. jejuni. The gene has two potential initiation codons, giving rise to two possible nested protein products. Complex differential growth-phase-dependent transcripts give rise to these products.

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On protein translocation across bacterial cytoplasmic membranes

Cited by 5 publications

References 34 publications

A role for Trigger Factor and an Rgg-like regulator in the transcription, secretion and processing of the cysteine proteinase ofStreptococcus pyogenes

A role for Trigger Factor and an Rgg-like regulator in the transcription, secretion and processing of the cysteine proteinase ofStreptococcus pyogenes

A Significant Fraction of Functional SecA Is Permanently Embedded in the Membrane

The gene for Campylobacter trigger factor: evidence for multiple transcription start sites and protein products

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