Gognies S, Gainvors A, Aigle M, Belarbi A
Université de Reims, Faculté des Sciences, Laboratoire de Microbiologie Générale et Moléculaire, Europol'Agro, France.
Yeast. 1999 Jan 15;15(1):11-22. doi: 10.1002/(SICI)1097-0061(19990115)15:1<11::AID-YEA336>3.0.CO;2-O.
Only a few yeast strains produce pectin-degrading enzymes such as pectin esterases and depolymerases (hydrolases and lyases). Strain SCPP is the only known Saccharomyces strain to produce these pectinases. One of these pectolytic enzymes. PGL1-encoded endopolygalacturonase (EC 3.2.1.15), hydrolyses the alpha-1,4-glycosidic bonds within the rhamnogalacturonan chains in pectic substances. This paper presents the cloning and sequencing of the first S. cerevisiae gene involved in pectin degradation. Few differences were found between the two deduced amino acid sequences encoded by PGL1-1 from a pectolytic (PG+) strain (SCPP) and PGL1-2 from a non-pectolytic (PG-) strain (X2180-1B). Similarities were found with other polygalacturonases from plants and other microorganisms. Of the two S. cerevisiae genes, only the one isolated from strain SCPP was able, by overexpression, to confer endopolygalacturonase activity to a laboratory strain of S. cerevisiae. Overexpression of PGL1-1 gene in a non-pectolytic strain resulted in halo formation on polygalacturonic acid-containing agar plates stained with ruthenium red.
只有少数酵母菌株能产生果胶降解酶，如果胶酯酶和果胶解聚酶（水解酶和裂解酶）。SCPP菌株是已知唯一能产生这些果胶酶的酿酒酵母菌株。其中一种果胶分解酶，即由PGL1编码的内切多聚半乳糖醛酸酶（EC 3.2.1.15），可水解果胶物质中鼠李糖半乳糖醛酸聚糖链内的α-1,4-糖苷键。本文介绍了首个参与果胶降解的酿酒酵母基因的克隆和测序。在果胶分解（PG+）菌株（SCPP）的PGL1-1和非果胶分解（PG-）菌株（X2180-1B）的PGL1-2所编码的两个推导氨基酸序列之间，发现的差异很少。与来自植物和其他微生物的其他多聚半乳糖醛酸酶存在相似性。在这两个酿酒酵母基因中，只有从SCPP菌株分离出的那个基因，通过过表达，能够赋予酿酒酵母实验室菌株内切多聚半乳糖醛酸酶活性。在不含果胶分解酶的菌株中过表达PGL1-1基因，在用钌红染色的含聚半乳糖醛酸的琼脂平板上会形成晕圈。
