Analysis of Escherichia coli K12 F factor transfer genes: traQ, trbA, and trbB

Wu, June H.; Moore, Deanna; Lee, Tammy; Ippen‐Ihler, Karin

doi:10.1016/0147-619x(87)90078-3

Cited by 26 publications

(42 citation statements)

References 26 publications

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“…On well-resolved gels of radioactively labeled membrane protein preparations, the 7-kDa pilin polypeptide synthesized in the Hfr deletion strains also migrated slightly faster than the wild-type Ac-7 pilin subunit (data not shown). This trait is typical of the unmodified 7(Q) product synthesized when only traA and traQ are expressed (23,49).…”

Section: Resultsmentioning

confidence: 99%

“…Since the products of both traX and traQ appear to be inner membrane proteins (4,48,49), these proteins may normally be associated with each other. TraQ prevents degradation of the traA product and may assist membrane entry of the pilin precursor in a conformation appropriate for signal-peptide cleavage (23,24).…”

Section: Discussionmentioning

confidence: 99%

“…Laine et al also detected small amounts of an 8-kDa traA product (Ap8) (23 F pili or detectable quantities of F-pilin subunits (22). Thus, the traQ product, a 94-amino-acid inner membrane protein (48,49), appears to be required for efficient utilization and processing of the pilin precursor. It was suggested that Ap8 might be an intermediate in such processing (23).…”

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confidence: 98%

“…When an Flac traA host was used, the pilin expressed from the phages comigrated with wild-type pilin and was readily precipitable with the serum. In an Fhost, plasmids expressing cloned traA and traQ sequences also expressed the faster-migrating polypeptide, 7(Q) (49). Thus, it appeared that the product of a third F gene modified the pilin polypeptide.…”

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confidence: 98%

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The Escherichia coli K-12 F plasmid gene traX is required for acetylation of F pilin

et al. 1993

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The Escherichia coli F plasmid gene required for amino-terminal acetylation of F-pilin subunits was identified. Using Western blots (immunoblots), we assayed the reaction of monoclonal antibodies with F-pilin polypeptides in inner membrane preparations from various F mutant strains. It was known that JEL92 recognizes an internal pilin epitope and JEL93 recognizes the acetylated amino-terminal sequence (L.S. Frost, J.S. Lee, D.G. Scraba, and W. Paranchych, J. Bacteriol. 168:192-198, 1986). As expected, neither antibody reacted with inner membranes from F- cells or Flac derivatives that do not synthesize pilin. Mutations that affected the individual activities of F tra genes traA, -B, -C, -D, -E, -F, -G, -H, -I, -J, -K, -L, -M, -N, -P, -R, -U, -V and -W or trb genes trbA, -B, -C, -D, -E, -G, -H, and -I did not prevent JEL92 or JEL93 recognition of membrane pilin. However, Hfr deletion mutants that lacked the most-distal transfer region genes did not express pilin that reacted with JEL93. Nevertheless, all strains that retained traA and traQ did express JEL92-reactive pilin polypeptides. Analysis of strains expressing cloned tra segments showed that traA and traQ suffice for synthesis of JEL92-reactive pilin, but synthesis of JEL93-reactive pilin is additionally dependent on traX. We concluded that the traX product is required for acetylation of F pilin. Interestingly, our data also showed that TraA+ TraQ+ cells synthesize two forms of pilin which migrate at approximately 7 and 8 kDa. In TraX+ cells, both become acetylated and react with JEL93. Preparations of wild-type F-pilus filaments contain both types of subunits.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 98%

mentioning

confidence: 98%

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The Escherichia coli K-12 F plasmid gene traX is required for acetylation of F pilin

et al. 1993

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“…For this purpose, we have been analyzing the protein products and tra mutant-complementirng activities expressed by plasmids carrying cloned F DNA fragments. Such studies have revealed that the F tra region contains a number of genes that had not been identified by earlier mutational analyses (9,31,39,41). Since mutants containing defects in these genes had not been isolated, the requirement for these genes in conjugative processes has remained to be demonstrated.…”

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confidence: 99%

Characterization of trbC, a new F plasmid tra operon gene that is essential to conjugative transfer

Maneewannakul

Ippen‐Ihler

1991

J Bacteriol

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We have characterized a previously unidentified gene, trbC, which is contained in the transfer region of the Escherichia coi K-12 fertility factor, F. Our data show that the trbC gene is located between the F plasmid genes traU and traN. The product of trbC was identified as a polypeptide with an apparent molecular weight (M. amino-terminal signal sequence. We also constructed two different Km' gene insertion mutations in trbC and crossed these onto the transmissible F plasmid derivative pOX38. We found that cells carrying pOX38 trbC mutant plasmids were transfer deficient and resistant to infection by F-pilus-specific phages. Transfer proficiency and bacteriophage sensitivity were restored by complementation when a trbC+ plasmid clone was introduced into these cells. These results showed that trbC function is essential to the F plasmid conj,ugative

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