Post‐transcriptional control in the polycistronic operon environment: studies of the <i>atp</i> operon of <i>Escherichia coli</i>

McCarthy, John E.G.

doi:10.1111/j.1365-2958.1990.tb00702.x

Cited by 48 publications

(34 citation statements)

References 37 publications

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“…4). It is possible that the processed mRNA products undergo rapid degradation by exonucleolytic cleavage, therefore becoming invisible on the Northern blots (28). It is noteworthy that the mRNA ratio of the major transcripts (AIAB/ABC/ABCD) remains relatively unchanged throughout the growth cycle.…”

Section: Discussionmentioning

confidence: 97%

Regulation of plasmid virulence gene expression in Salmonella dublin involves an unusual operon structure

1992

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Section: Discussionmentioning

confidence: 97%

Regulation of plasmid virulence gene expression in Salmonella dublin involves an unusual operon structure

1992

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“…It was unexpected to find tatE cotranscribed with genes for N 2 OR maturation. A different stoichiometry required for the different functions encoded in polycistronic messages can be achieved by posttranscriptional control mechanisms, as exemplified for the ATPase operon of E. coli (30,31) or the histidine transport operon of S. enterica serovar Typhimurium (41). The nosD operon thus may be subjected to regulation of translational efficiency or the stability of distinct mRNA segments.…”

Section: Discussionmentioning

confidence: 99%

Operon Structure and Regulation of the nos Gene Region of Pseudomonas stutzeri , Encoding an ABC-Type ATPase for Maturation of Nitrous Oxide Reductase

Honisch

Zumft

2003

J Bacteriol

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The synthesis of a functional nitrous oxide reductase requires an assembly apparatus for the insertion of the prosthetic copper. Part of the system is encoded by maturation genes located in Pseudomonas stutzeri immediately downstream of the structural gene for the enzyme. We have studied the transcriptional organization and regulation of this region and found a nosDFYL tatE operon structure. In addition to a putative ABC transporter, consisting of NosD, NosF, and NosY, the operon encodes a Cu chaperone, NosL, and a component of the Tat translocon, TatE. The nosD operon was activated in response to anaerobiosis and nitrate denitrification. The membrane-bound regulator NosR was required for operon expression; in addition, DnrD, a regulator of the Crp-Fnr family, enhanced expression under anaerobic conditions. This establishes a likely signal transduction sequence of NO 3 DnrD 3 nosR/NosR 3 nosD operon. DnrD-dependent expression was also observed for the nnrS operon (located immediately downstream of the nosD operon), which encodes a putative heme-Cu protein (NnrS) and a member of the short-chain dehydrogenase family (ORF247). The NosF protein, encoded within the nosD operon, exhibits sequence similarity to ABC-type ATPases. It was fused to the Escherichia coli maltose-binding protein and overexpressed in soluble form. The fusion protein was purified and shown to have ATPase activity. NosF is the first maturation factor for which a catalytic function has been demonstrated in vitro.The multicopper enzyme nitrous oxide reductase (N 2 OR) undergoes a maturation process for the insertion of its prosthetic metal (32,39,44,48,49). Several accessory proteins are required for the biosynthesis of the catalytically active enzyme, some of which are encoded by genes located downstream of the N 2 OR structural gene, nosZ. Expression of nosZ is dependent on the multitopic, membrane-bound regulator NosR (10). At least three proteins, encoded by the maturation genes nosD, -F, and -Y, form a putative assembly complex which extends to both sides of the cytoplasmic membrane. From sequence similarity, it was inferred that nosF may encode an ATP/GTPase and that a step in the biosynthesis of N 2 OR is energy dependent (49). A lacZ reporter gene fusion had been used to deduce a location in the cytoplasm for NosF (9). NosD belongs to a family of proteins with a carbohydrate binding and sugar hydrolase domain (8) whose significance is still unclear. NosY is a six-helix transmembrane protein; it is presumed that, together with NosF and periplasmic NosD, it forms an ABC-type transporter. The biosynthesis of N 2 OR also involves a number of additional factors which are nonessential or can be functionally replaced by other cellular processes (44).Catalyzed assembly of the prosthetic Cu in N 2 OR seems to be obligatory for the Cu Z center, representing the catalytic site in the form of a tetranuclear CuS cluster (6, 35), rather than for the binuclear Cu A center, which represents the electron entry site (27). Mutational inactivation of any of t...

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“…4). This suggests that translation of all four ORFs is coupled (33,34). Table 2 lists the predicted molecular masses deduced from the amino acid sequences of the ORFs.…”

Section: Methodsmentioning

confidence: 99%

Characterization of the rfc region of Shigella flexneri

et al. 1994

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The 0 antigen of the ShigeUla flexneri lipopolysaccharide (LPS) is an important virulence determinant and immunogen. We have isolated S. flexneri mutants which produce a semi-rough LPS by using an 0-antigenspecific phage, Sf6c. Western immunoblotting was used to show that the LPS produced by the semi-rough mutants contained only one 0-antigen repeat unit. Thus, the mutants are deficient in production of the 0-antigen polymerase and were termed rfc mutants. Complementation experiments were used to locate the r*c adjacent to the rjb genes on plasmid clones previously isolated and containing this region (D. F. Macpherson, R. Morona, D. W. Beger, K.-C. Cheah, and P. A. Manning, Mol. Microbiol 5:1491-1499 downstream of the rfc gene could be identified. Examination of the distribution of rare or minor codons in the rfc gene revealed that it has several minor codons within the first 25 amino acids. This is in contrast to the upstream gene rJbG, which also has a high percentage of rare codons but whose gene product could be detected.The positioning of the rare codons in the rfc gene may restrict translation and suggests that minor isoaccepting tRNA species may be involved in translational regulation of rfc expression. The low percentage of G+C content of rfc genes may be a consequence of the selection pressure to maintain this form of control.The lipopolysaccharide (LPS) of gram-negative bacteria constitutes a major protective barrier against dyes, detergents, and hydrophobic agents. The 0 antigen of the LPS of Shigella flexneri is a virulence determinant (27,32), and immune responses against this antigen correlate with immunity to shigellosis (4,8,9). As with many other members of the family Enterobacteriaceae, the 0 antigen is encoded by the rfb locus near his (45, 49) on the chromosome. This locus encodes enzymes which synthesize the nucleotide-activated sugar precursor (dTDP-rhamnose) (30) and nucleotide sugar transferases, which assemble onto the lipid carrier bactoprenol, a tetrasaccharide repeat unit with the following structure: rhamnose-rhamnose-rhamnose-N-acetylglucosamine. This tetrasaccharide repeat unit is then polymerized by the 0-antigen polymerase into long chains. An 0-antigen ligase covalently attaches these units onto incomplete LPS molecules composed of lipid A and core sugars (21).Several phenotypes related to the structure of LPS molecules are recognized. The wild-type LPS pattern observed after silver staining of LPS separated by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) is termed smooth LPS (S-LPS distribution of 0-antigen chain lengths with an average of about 12 to 17 0-antigen tetrasaccharide repeat units. A variation of this has been observed in Escherichia coli K-12 cells harboring the cloned S. flexneri rfb genes but lacking the rol (31) gene. In this case, the 0-antigen chain lengths are more or less randomly distributed. LPS molecules which lack 0 antigen are termed rough (R-LPS) and can be visualized as multiple bands migrating near the dye front by silver s...

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Post‐transcriptional control in the polycistronic operon environment: studies of the atp operon of Escherichia coli

Cited by 48 publications

References 37 publications

Regulation of plasmid virulence gene expression in Salmonella dublin involves an unusual operon structure

Regulation of plasmid virulence gene expression in Salmonella dublin involves an unusual operon structure

Operon Structure and Regulation of the nos Gene Region of Pseudomonas stutzeri , Encoding an ABC-Type ATPase for Maturation of Nitrous Oxide Reductase

Characterization of the rfc region of Shigella flexneri

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