Distinct regulators control the expression of methanol methyltransferase isozymes in Methanosarcina acetivorans C2A

Department of Microbiology, University of Illinois at Urbana-Champaign, B103 CLSL, 601 S. Goodwin, Urbana, IL 61801, USA.
Molecular Microbiology (Impact Factor: 5.03). 03/2008; 67(3):649-61. DOI: 10.1111/j.1365-2958.2007.06075.x
Source: PubMed

ABSTRACT The mtaCB1, mtaCB2 and mtaCB3 operons encode isozymes of methanol methyltransferases in Methanosarcina acetivorans C2A and are among the most highly regulated genes known in Archaea. Here we identify cis and trans acting elements that affect the expression of these operons. In vivo reporter gene constructs expressed from sequentially truncated promoters show that the mRNA transcripts for these operons have large 5' untranslated regions. Regions upstream of the transcription start site (TSS) are important for induction of the mtaCB1 and mtaCB2 operons and for repression of the mtaCB3. Regions downstream of the TSS are important for expression of the mtaCB2 and mtaCB3 operons, but are dispensable for mtaCB1 expression. Proteins encoded by the MA0459 and MA0460 loci are required for induction of the mtaCB1 operon, while those encoded by MA4383, MA4397 and MA4398 are required for induction of mtaCB2. Proteins encoded by MA4397 and MA4398 are also required for methanol-specific repression of the mtaCB3 operon and, thus, are the first archaeal examples of regulatory proteins that simultaneously act in both repression and activation. We refer to these genes as methanol-specific regulators and designate MA0459, MA0460, MA4383, MA4397 and MA4398 as msrA, msrB, msrC, msrD and msrE respectively.

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    • "RLM-RACE was performed as previously described with minor changes described in the supporting information (Bose and Metcalf, 2008). cRACE was performed as described previously with minor modifications described in the supporting information (Maruyama et al., 1995, Main-Hester et al., 2008; Rey and Harwood, 2010). "
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    • "Although unaffected on most growth substrates, each of the three mutant strains exhibit longer generation times on MMA (~2-fold longer for DmsrF and DmsrG and ~5-fold longer for DmsrC). We had observed previously that DmsrC had a slightly longer generation time on methanol compared with WWM82, which was confirmed in this study (Bose and Metcalf, 2008). These data suggest that the targets of the regulatory proteins play an important role during growth on these substrates. "
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