Nonproteolytic cleavage of aspartyl proline bonds in the cellulosomal scaffoldin subunit from Clostridium thermocellum
Nonproteolytic cleavage of aspartyl proline bonds in the cellulosomal scaffoldin subunit from Clostridium thermocellum
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DOI：
10.1385/abab:90:1:67
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发表时间：
2001-01-01
影响因子：
3
通讯作者：
Bayer, EA
中科院分区：
文献类型：
--
作者：
Lamed, R;Kenig, R;Bayer, EA
我们小组以前的工作[莫拉格（摩根斯坦），E.，拜尔，E.一、和La Med，R.（1991），Appl.Biochem.Biotechnol. 30，129-136]已经证明了支架蛋白（热纤梭菌的210-kDa纤维素体整合亚基）的异常电泳迁移率模式。后来的证据[莫拉格，E.，拜尔，E.一、和Lamed，R.（1992），Appl.Biochem.Biotechnol. 33，205-217]表明，该效应可能归因于亚基的非蛋白水解片段化成一系列确定的较低分子量条带。在本工作中，采用支架蛋白亚基的重组片段来确定键断裂的位点。在粘附素结构域内的Asp-Pro序列被鉴定为敏感的肽键。该序列在大纤维素体蛋白中出现得相当频繁，并且该不稳定键可能与纤维素体水解纤维素中尚未描述的生理作用有关。
Previous work from our group [Morag (Morgenstern), E., Bayer, E. A., and La med, R. (1991), Appl. Biochem. Biotechnol. 30, 129-136] has demonstrated an anomalous electrophoretic mobility pattern for scaffoldin, the 210-kDa cellulosome-integrating subunit of Clostridium thermocellum. Subsequent evidence [Morag, E., Bayer, E. A., and Lamed, R. (1992), Appl. Biochem. Biotechnol. 33, 205-217] indicated that the effect could be attributed to a nonproteolytic fragmentation of the subunit into a defined series of lower-molecular-weight bands. In the present work, a recombinant segment of the scaffoldin subunit was employed to determine the site(s) of bond breakage. An Asp-Pro sequence within the cohesin domain was identified to be the sensitive peptide bond. This sequence appears quite frequently in the large cellulosomal proteins, and the labile bond may be related to an as yet undescribed physiological role in the hydrolysis of cellulose by cellulosomes.