Randall K, Lever M, Peddie B A, Chambers S T
Department of Clinical Biochemistry, Christchurch Hospital, New Zealand.
Biochim Biophys Acta. 1995 Aug 17;1245(1):116-20. doi: 10.1016/0304-4165(95)00071-i.
Escherichia coli was grown in hyperosmotic media containing both glycine betaine and one other betaine. E. coli K-12 derivative WG439 (putP- proP- proU-) did not accumulate any of 15 betaines. Strains WG445 (putP- proP- proU+), WG443 (putP- proP+ proU-) and the control strains all accumulated less betaine, (CH3)3N(+)-(CH2)n-COO-, when n was greater than 1. Accumulation was not detectable when n = 5. Both L- and D-isomers of alpha-substituted betaines were accumulated by both strains WG443 and WG445, the D-isomers more slowly. Hydroxylated alpha-substituted betaines were accumulated relatively more through the osmoregulated transport protein ProU than through ProP. In actively growing cultures glycine betaine appeared to be the preferred substrate for accumulation, but the proportion of the second accumulated betaine increased as cultures approached stationary phase.
大肠杆菌在含有甘氨酸甜菜碱和另一种甜菜碱的高渗培养基中培养。大肠杆菌K - 12衍生物WG439（putP - proP - proU -）不会积累15种甜菜碱中的任何一种。菌株WG445（putP - proP - proU +）、WG443（putP - proP + proU -）和对照菌株在n大于1时积累的甜菜碱（(CH3)3N(+)-(CH2)n - COO -）都较少。当n = 5时，积累量无法检测到。WG443和WG445菌株都能积累α - 取代甜菜碱的L - 异构体和D - 异构体，D - 异构体积累得较慢。与通过ProP相比，羟基化α - 取代甜菜碱通过渗透调节转运蛋白ProU积累得相对更多。在活跃生长的培养物中，甘氨酸甜菜碱似乎是积累的首选底物，但随着培养物接近稳定期，第二种积累的甜菜碱的比例会增加。
