May W S, Formica J V
J Bacteriol. 1978 May;134(2):546-54. doi: 10.1128/jb.134.2.546-554.1978.
Streptomyces antibioticus possesses an energy-dependent, carrier mediated transport system for the uptake of L-glutamate and L-proline. Amino acid transport was found to have a temperature optimum of 35 degrees C and a pH optimum from 7.0 to 8.0 for glutamate and 6.5 to 7.5 for proline uptake. Uptake did not depend upon Mg2+, Ca2+, Zn2+, Na+, or Fe2+ ions. Reversible p-hydroxymercuribenzoate inhibition of uptake indicated the involvement of an active sulfhydryl group. L-Glutamate uptake was mediated by a glutamate-inducible, nonspecific transport system, which was extremely stable and was not subject to substrate inhibition by L-proline. On the other hand, L-proline transport was mediated by at least two systems. The L-glutamate-inducible nonspecific system can account for uptake of proline by the mycelium grown in glutamate. In addition, a proline-specific, constitutive transport system was found to be present in the mycelium grown in organic and inorganic nitrogen sources other than L-glutamate. Shift experiments revealed that proline transport is not as stable as glutamate transport when the glutamate-inducible nonspecific system is utilized.
抗生链霉菌拥有一种能量依赖型、载体介导的转运系统，用于摄取L-谷氨酸和L-脯氨酸。发现氨基酸转运的最适温度为35℃，摄取谷氨酸时的最适pH为7.0至8.0，摄取脯氨酸时的最适pH为6.5至7.5。摄取不依赖于Mg2+、Ca2+、Zn2+、Na+或Fe2+离子。对摄取的可逆对羟基汞苯甲酸抑制表明有活性巯基参与。L-谷氨酸的摄取由谷氨酸诱导的非特异性转运系统介导，该系统极其稳定，不受L-脯氨酸的底物抑制。另一方面，L-脯氨酸的转运由至少两个系统介导。L-谷氨酸诱导的非特异性系统可以解释在谷氨酸中生长的菌丝体对脯氨酸的摄取。此外，发现脯氨酸特异性组成型转运系统存在于在除L-谷氨酸以外的有机和无机氮源中生长的菌丝体中。转移实验表明，当利用谷氨酸诱导的非特异性系统时，脯氨酸转运不如谷氨酸转运稳定。
