谷氨酰胺合成酶
氮气
生物化学
氮同化
铵
蓝藻
氮气循环
亚硝酸盐还原酶
亚硝酸盐
生物
精氨酸酶
化学
鱼腥藻
硝酸盐
精氨酸
谷氨酸合酶
硝酸还原酶
谷氨酰胺
酶
氨基酸
细菌
生态学
有机化学
遗传学
作者
Enrique Flores,Antonia Herrero
出处
期刊:Biochemical Society Transactions
[Portland Press]
日期:2005-02-01
卷期号:33 (1): 164-167
被引量:270
摘要
Nitrogen sources commonly used by cyanobacteria include ammonium, nitrate, nitrite, urea and atmospheric N2, and some cyanobacteria can also assimilate arginine or glutamine. ABC (ATP-binding cassette)-type permeases are involved in the uptake of nitrate/nitrite, urea and most amino acids, whereas secondary transporters take up ammonium and, in some strains, nitrate/nitrite. In cyanobacteria, nitrate and nitrite reductases are ferredoxin-dependent enzymes, arginine is catabolized by a combination of the urea cycle and arginase pathway, and urea is degraded by a Ni2+-dependent urease. These pathways provide ammonium that is incorporated into carbon skeletons through the glutamine synthetase–glutamate synthase cycle, in which 2-oxoglutarate is the final nitrogen acceptor. The expression of many nitrogen assimilation genes is subjected to regulation being activated by the nitrogen-control transcription factor NtcA, which is autoregulatory and whose activity appears to be influenced by 2-oxoglutarate and the signal transduction protein PII. In some filamentous cyanobacteria, N2 fixation takes place in specialized cells called heterocysts that differentiate from vegetative cells in a process strictly controlled by NtcA.
科研通智能强力驱动
Strongly Powered by AbleSci AI