This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Klug, G Articles by Jock, S Search for Related Content PubMed PubMed Citation Articles by Klug, G Articles by Jock, S

research-article

A base pair transition in a DNA sequence with dyad symmetry upstream of the puf promoter affects transcription of the puc operon in Rhodobacter capsulatus.

Zentrum für Molekulare Biologie, Heidelberg, Germany.

ABSTRACT

A DNA sequence with dyad symmetry upstream of the transcriptional start of the Rhodobacter capsulatus puf operon, which encodes pigment-binding proteins of the light-harvesting I complex and of the reaction center, has previously been shown to be a protein-binding site (G. Klug, Mol. Gen. Genet. 226:167-176, 1991). When a low-copy-number plasmid with a base pair transition at position -43 within this dyad symmetry in front of the puf structural genes was transferred into a Rhodobacter strain with the puf operon deleted, different phenotypes occurred during cultivation of the transconjugants and the kinetics of the loss of the wild-type phenotype was dependent on the oxygen tension in the culture. After growth for 150 generations, the different phenotypes were stably inherited. The strains having the wild-type phenotype carried the wild-type puf DNA sequence. The original mutation was still present in the strains that showed lighter color. These strains had less light-harvesting II complex in the membrane and showed lower rates of transcription of the puc operon, which encodes the proteins of this complex. This deregulation of puc expression was due to one or more chromosomally located, secondary mutations, not directly to the mutation present on the plasmid. Thus, a single-base-pair transition in the puf upstream region can result in a deregulation of puc expression, suggesting a direct or indirect transcriptional coregulation of both these operons by a common factor.

This article has been cited by other articles:

• Dong, C., Elsen, S., Swem, L. R., Bauer, C. E. (2002). AerR, a Second Aerobic Repressor of Photosynthesis Gene Expression in Rhodobacter capsulatus. J. Bacteriol. 184: 2805-2814 [Abstract] [Full Text]