Three multidomain esterases from the cellulolytic rumen anaerobe Ruminococcus flavefaciens 17 that carry divergent dockerin sequences
Three multidomain esterases from the cellulolytic rumen anaerobe Ruminococcus flavefaciens 17 that carry divergent dockerin sequences
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DOI：
10.1099/00221287-146-6-1391
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发表时间：
2000-06-01
期刊：
影响因子：
2.8
通讯作者：
Flint, HJ
中科院分区：
文献类型：
--
作者：
Aurilia, V;Martin, JC;Flint, HJ
新鉴定的CesA基因产物（768个氨基酸）包括一个n端乙酰酯酶结构域和一个未知的c端结构域，而先前鉴定的XynB酶（781个氨基酸）除了其n端木聚糖酶催化结构域外，还包括一个内部乙酰酯酶结构域。第三个基因，xynE，预计编码792个氨基酸的多结构域酶，包括11家族木聚糖酶结构域和c端酯酶结构域。CesA和XynB的酯酶结构域具有显著的序列一致性（44%），属于碳水化合物酯酶家族3；这两个结构域都显示能够使乙酰化木聚糖去乙酰化，但没有证据表明阿魏酸酯酶活性。然而，XynE的酯酶结构域与热cellum Clostridum XynZ， XynB， XynE和CesA的1家族酚酸酯酶结构域具有42%的氨基酸一致性，除了它们的催化结构域外，它们都含有dockerin-like区域，这表明这些酶构成了类似纤维素体的多酶复合物的一部分。CesA和XynE的dockerin序列与先前在R， flavefaciens多糖酶（包括XynB）中描述的dockerin序列有很大不同，这表明它们可能代表不同的dockerin特异性。
Three enzymes carrying esterase domains have been identified in the rumen cellulolytic anaerobe Ruminococcus flavefaciens 17, The newly characterized CesA gene product (768 amino acids) includes an N-terminal acetylesterase domain and an unidentified C-terminal domain, while the previously characterized XynB enzyme (781 amino acids) includes an internal acetylesterase domain in addition to its N-terminal xylanase catalytic domain. A third gene, xynE, is predicted to encode a multidomain enzyme of 792 amino acids including a family 11 xylanase domain and a C-terminal esterase domain. The esterase domains from CesA and XynB share significant sequence identity (44%) and belong to carbohydrate esterase family 3; both domains are shown here to be capable of deacetylating acetylated xylans, but no evidence was found for ferulic acid esterase activity. The esterase domain of XynE, however, shares 42 % amino acid identity with a family 1 phenolic acid esterase domain identified from Clostridum thermocellum XynZ, XynB, XynE and CesA all contain dockerin-like regions in addition to their catalytic domains, suggesting that these enzymes form part of a cellulosome-like multienzyme complex. The dockerin sequences of CesA and XynE differ significantly from those previously described in R, flavefaciens polysaccharidases, including XynB, suggesting that they might represent distinct dockerin specificities.