Glycine betaine loses its osmoprotective activity in a bspA strain of Erwinia chrysanthemi

Touze, T Gouesbet, G Bolangiu, C Jebbar, M Bonnassie, S Blanco, C

T. Touze et al., Glycine betaine loses its osmoprotective activity in a bspA strain of Erwinia chrysanthemi, MOL MICROB, 42(1), 2001, pp. 87-99

49

INGLESE

Article

Microbiology

MOLECULAR MICROBIOLOGY

0950-382X → ACNP

42

1

2001

87 - 99

ISI

0950-382X(200110)42:1<87:GBLIOA>2.0.ZU;2-C

Erwinia chrysanthemi insertion mutants were isolated that grew poorly speci fically in the presence of glycine betaine (GB) or its analogues in high-sa lt media. Transposon insertions were found to affect the bspA gene, which f orms an operon including the psd locus coding for phosphatidylserine decarb oxylase. Initial GB uptake is not affected by the bspA mutation. However, i n high-salt medium, its initial accumulation is followed by a reduced gluco se uptake and a release of GB but not a loss of viability. BspA is homologo us to the widespread MscS channel, YggB, but does not seem to constitute a mechanosensitive channel. We suggest that BspA is a protein sensing both in tracellular GB and the extracellular salt content of the medium, the hypoth esis being built on the observation that BspA is necessary to maintain the GB pool during osmoadaptation in high-salt media containing this osmoprotec tant.