A THERMOLABILE TRIOSEPHOSPHATE ISOMERASE FROM THE PSYCHROPHILE VIBRIOSP STRAIN ANT-300

We report the isolation of a gene encoding triosephosphate isomerase ( TIM; EC 5.3.1.1) from Vibrio sp. strain ANT-300, a psychrophilic marin e eubacterium that grows optimally at 7 degrees C. The deduced primary sequence of this isomerase is 50% identical to Escherichia coli TIM a nd 37% identical to the isomerase of the psychrotroph Moraxella sp, TA 137. Transformation with this gene allowed growth of a TIM-deficient E . coli strain on selective media, but only at temperatures below 30 de grees C. The temperature dependence of this complementation is likely to result from an intrinsic thermolability of the isomerase. Indeed, t he TIM activity present in ANT-300 lysates is markedly heat-sensitive, with a half-life of inactivation of 520 s at 25 degrees C, (C) 1995 A cademic Press, Inc.