Mannosylglycerate is essential for osmotic adjustment in Thermus thermophilus strains HB27 and RQ-1.
We disrupted the mpgS encoding mannosyl-3-phosphoglycerate synthase (MpgS) of Thermus thermophilus strains HB27 and RQ-1, by homologous recombination, to assess the role of the compatible solute mannosylglycerate (MG) in osmoadaptation of the mutants, to examine their ability to grow in NaCl-containing medium and to identify the intracellular organic solutes. Strain HB27 accumulated only MG when grown in defined medium containing 2% NaCl; mutant HB27M9 did not grow in the same medium containing more than 1% NaCl. When trehalose or MG was added, the mutant was able to grow up to 2% of NaCl and accumulated trehalose or MG, respectively, plus amino acids. T. thermophilus RQ-1 grew in medium containing up to 5% NaCl, accumulated trehalose and lower amounts of MG. Mutant RQ-1M1 lost the ability to grow in medium containing more than 3% NaCl and accumulated trehalose and moderate levels of amino acids. Exogenous MG did not improve the ability of the organism to grow above 3% NaCl, but caused a decrease in the levels of amino acids. Our results show that MG serves as a compatible solute primarily during osmoadaptation at low levels of NaCl while trehalose is primarily involved in osmoadaptation during growth at higher NaCl levels.
Alarico
Susana
S
Departamento de Zoologia, Universidade de Coimbra, 3004-517, Coimbra, Portugal.
Empadinhas
Nuno
N
Mingote
Ana
A
Simões
Catarina
C
Santos
Maria S
MS
da Costa
Milton S
MS
D000222:Adaptation, Physiological; D000596:Amino Acids / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D005988:Glyceric Acids / Q000378:metabolism*; D008358:Mannose / Q000031:analogs & derivatives* / Q000378:metabolism; D008364:Mannosyltransferases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D012965:Sodium Chloride / Q000378:metabolism; D016963:Thermus thermophilus / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D014199:Trehalose / Q000378:metabolism; D014882:Water-Electrolyte Balance
D000596:Amino Acids; D001426:Bacterial Proteins; D005988:Glyceric Acids; C402688:mannosylglycerate; D012965:Sodium Chloride; D014199:Trehalose; D008364:Mannosyltransferases; C441639:mannosyl-3-phosphoglycerate synthase; D008358:Mannose