Pectate lyase 10A from Pseudomonas cellulosa is a modular enzyme containing a family 2a carbohydrate-binding module
Pectate lyase 10A from Pseudomonas cellulosa is a modular enzyme containing a family 2a carbohydrate-binding module
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DOI：
10.1042/0264-6021:3550155
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发表时间：
2001-04-01
影响因子：
4.1
通讯作者：
Black, GW
中科院分区：
文献类型：
--
作者：
Brown, IE;Mallen, MH;Black, GW
来自纤维假单胞菌的果胶酸裂解酶10A（Pel 10A）酶由649个残基组成，分子量为68.5kDa。序列分析表明，Pel 10A含有一个信号肽和两个富含丝氨酸的连接子序列，将三个模块分开。在Pel 10A的9.2kDa N-末端模块和家族2a碳水化合物结合模块（CBM）之间观察到序列相似性。Pel 10A的N-末端模块被证明编码对结晶纤维素具有亲和力的独立功能模块。一个高的序列一致性为66%之间的14.2 kDa的中央模块的佩尔10A和木聚糖降解酶内切木聚糖酶10 B，阿拉伯呋喃糖苷酶62 C和酯酶1D，也从P，cellulosa的功能不明的中央模块。Pel 10A的35.8kDa C-末端模块显示与来自Azoacellum irakense和芽孢杆菌属的嗜碱菌株KSM-P15的家族10果胶酸裂解酶分别具有30%和36%的同一性。Pel 10A的这种His标记的C-末端模块显示编码独立的催化模块（Pel 10Acm）。Pel 10Acm显示以内切方式切割果胶酸盐和果胶，并且在pH 10和2 mM Ca 2+存在下具有最佳活性。在62 ℃下检测到最高酶活性。Pel 10Acm显示出对果胶酸盐（即聚半乳糖醛酸）最有活性，而对31的活性逐渐降低。67度和89度（度），酯化柑橘果胶。这些数据表明，Pel 10A具有非酯化半乳糖醛酸残基序列的偏好。值得注意的是，在所附文章[McKie，Rumken，Voragen，货车den Broek，Stimson和吉尔伯特（2001）Biochem.J.355，167-177]中，Pel 10 A和P. cellulosa鼠李糖半乳糖醛酸聚糖裂解酶11 A是迄今为止描述的第一种含CBM的果胶酶。
Pectate lyase 10A (Pel10A) enzyme from Pseudomonas cellulosa is composed of 649 residues and has a molecular mass of 68.5 kDa. Sequence analysis revealed that Pel10A contained a signal peptide and two serine-rich linker sequences that separate three modules. Sequence similarity was seen between the 9.2 kDa N-terminal module of Pel10A and Family 2a carbohydrate-binding modules (CBMs). This N-terminal module of Pel10A was shown to encode an independently functional module with affinity to crystalline cellulose. A high sequence identity of 66% was seen between the 14.2 kDa central module of Pel 10A and the functionally uncharacterized central modules of the xylan-degrading enzymes endoxylanase 10B, arabinofuranosidase 62C and esterase 1D, also from P, cellulosa. The 35.8 kDa C-terminal module of Pel10A was shown to have 30 and 36% identities with the family 10 pectate lyases from Azospirillum irakense and an alkaliphilic strain of Bacillus sp. strain KSM-P15, respectively. This His-tagged C-terminal module of the Pel10A was shown encode an independent catalytic module (Pel10Acm). Pel10Acm was shown to cleave pectate and pectin in an endo-fashion and to have optimal activity at pH 10 and in the presence of 2 mM Ca2+. Highest enzyme activity was detected at 62 degreesC. Pel10Acm was shown to be most active against pectate (i.e. polygalacturonic acid) with progressively less activity against 31. 67 and 89 degrees (degrees), esterified citrus pectins. These data suggest that Pel10A has a preference for sequences of non-esterified galacturonic acid residues. Significantly, Pel10A and the P. cellulosa rhamnogalacturonan Lyase 11A, in the accompanying article [McKie, Vincken, Voragen, van den Broek, Stimson and Gilbert (2001) Biochem. J. 355, 167-177], are the first CBM-containing pectinases described to date.