Organic acid mediated repression of sugar utilization in rhizobia

详细信息    查看全文

• 作者：Bhagya Iyer^a ; Mahendrapal Singh Rajput^a ; Rahul Jog^a ; ^b ; Ekta Joshi^a ; Krishna Bharwad^a ; Shalini Rajkumar^a ; ^{shalini.rjk@nirmauni.ac.in" class="auth_mail" title="E-mail the corresponding author}
• 关键词：ABC ; ATP-binding cassette ; N2 ; nitrogen ; DNP ; 2 ; 4-dinitrophenol ; ED ; Entner-Doudoroff ; EMP ; Embden Meyerhof Paranas ; FBP ; fructose bisphosphatase ; FBPA ; fructose bisphosphate aldolase ; ICL ; isocitrate lyase ; KCN ; potassium cyanide ; PBP ; periplasmic binding protein ; PEPCK ; phosphoenolpyruvate carboxykinase ; PP ; pentose phosphate ; TRAP ; tripartite ; ATP ; independent periplasmic ; PTS ; phosphotransferase system ; SMCR ; succinate mediated catabolite repression ; TCA ; tricarboxylic acid
• 刊名：Microbiological Research
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：192
• 期：Complete
• 页码：211-220
• 全文大小：1737 K

文摘

Rhizobia are a class of symbiotic diazotrophic bacteria which utilize C₄ acids in preference to sugars and the sugar utilization is repressed as long as C₄ acids are present. This can be manifested as a diauxie when rhizobia are grown in the presence of a sugar and a C₄ acid together. Succinate, a C₄ acid is known to repress utilization of sugars, sugar alcohols, hydrocarbons, etc by a mechanism termed as Succinate Mediated Catabolite Repression (SMCR). Mechanism of catabolite repression determines the hierarchy of carbon source utilization in bacteria. Though the mechanism of catabolite repression has been well studied in model organisms like E. coli, B. subtilis and Pseudomonas sp., mechanism of SMCR in rhizobia has not been well elucidated. C₄ acid uptake is important for effective symbioses while mutation in the sugar transport and utilization genes does not affect symbioses. Deletion of hpr and sma0113 resulted in the partial relief of SMCR of utilization of galactosides like lactose, raffinose and maltose in the presence of succinate. However, no such regulators governing SMCR of glucoside utilization have been identified till date. Though rhizobia can utilize multitude of sugars, high affinity transporters for many sugars are yet to be identified. Identifying high affinity sugar transporters and studying the mechanism of catabolite repression in rhizobia is important to understand the level of regulation of SMCR and the key regulators involved in SMCR.