Specific amino acid substitutions in the proline-rich motif of the Rhizobium meliloti ExoP protein result in enhanced production of low-molecular-weight succinoglycan at the expense of high-molecular-weight succinoglycan.
The production of the acidic exopolysaccharide succinoglycan (EPS I) by Rhizobium meliloti exoP* mutants expressing an ExoP protein lacking its C-terminal cytoplasmic domain and by mutants characterized by specific amino acid substitutions in the proline-rich motif (RX4PX2PX4SPKX9IXGXMXGXG) located from positions 443 to 476 of the ExoP protein was analyzed. The absence of the C-terminal cytoplasmic ExoP domain (positions 484 to 786) and the substitution of both arginine443 by isoleucine443 and proline457 by serine457 within the proline-rich motif resulted in enhanced production of low-molecular-weight (LMW) EPS I at the expense of high-molecular-weight (HMW) EPS I. The ratios of HMW to LMW EPS I of the wild type and mutant strains increased with osmolarity.
Becker
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Lehrsthul für Genetik, Fakultät für Biologie, Universität Bielefeld, Germany. hippo@genetik.uni-bielefeld.de
Pühler
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D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000737:chemistry; D011392:Proline / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D016962:Sinorhizobium meliloti / Q000378:metabolism*
D001426:Bacterial Proteins; C095765:ExoP protein, Rhizobium meliloti; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D011135:Polysaccharides, Bacterial; C056779:succinoglycan; D011392:Proline