Annotating Enzymes of Unknown Function: N-Formimino-L-glutamate Deiminase Is a Member of the Amidohydrolase Superfamily

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• 作者：Ricardo Martí ; -Arbona ; Chengfu Xu ; Sondra Steele ; Amanda Weeks ; Gabriel F. Kuty ; Clara M. Seibert ; and Frank M. Raushel
• 刊名：Biochemistry
• 出版年：2006
• 出版时间：February 21, 2006
• 年：2006
• 卷：45
• 期：7
• 页码：1997 - 2005
• 全文大小：453K
• 年卷期：v.45,no.7(February 21, 2006)
• ISSN：1520-4995

文摘

The functional assignment of enzymes that catalyze unknown chemical transformations is adifficult problem. The protein Pa5106 from Pseudomonas aeruginosa has been identified as a member ofthe amidohydrolase superfamily by a comprehensive amino acid sequence comparison with structurallyauthenticated members of this superfamily. The function of Pa5106 has been annotated as a probablechlorohydrolase or cytosine deaminase. A close examination of the genomic content of P. aeruginosareveals that the gene for this protein is in close proximity to genes included in the histidine degradationpathway. The first three steps for the degradation of histidine include the action of HutH, HutU, and HutIto convert L-histidine to N-formimino-L-glutamate. The degradation of N-formimino-L-glutamate toL-glutamate can occur by three different pathways. Three proteins in P. aeruginosa have been identifiedthat catalyze two of the three possible pathways for the degradation of N-formimino-L-glutamate. Theprotein Pa5106 was shown to catalyze the deimination of N-formimino-L-glutamate to ammonia andN-formyl-L-glutamate, while Pa5091 catalyzed the hydrolysis of N-formyl-L-glutamate to formate andL-glutamate. The protein Pa3175 is dislocated from the hut operon and was shown to catalyze the hydrolysisof N-formimino-L-glutamate to formamide and L-glutamate. The reason for the coexistence of two alternativepathways for the degradation of N-formimino-L-glutamate in P. aeruginosa is unknown.