New insights into substrate folding preference of plant OSCs  

作　　者：Yongshuo Ma Yuan Zhou Sergey Ovchinnikov Per Jr.Greisen Sanwen Huang Yi Shang 

机构地区：[1]Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops of the Ministry of Agriculture, Sino-Dutch Joint Laboratory of Horticultural Genomics [2]Department of Biochemistry, University of Washington [3]Department of Modelling, Novo Nordisk A/S, 2760 Ml?v,Denmark [4]Agricultural Genomic Institute at Shenzhen, Chinese Academy of Agricultural Sciences

出　　处：《Science Bulletin》2016年第18期1407-1412,共6页科学通报（英文版）

基　　金：supported by funding from the National Natural Science Foundation of China (31401886);the Agricultural Science and Technology Innovation Program

摘　　要：Sterols and triterpenes are structurally diverse bioactive molecules generated through cyclization of linear 2,3-oxidosqualene. Based on carbocationic intermediates generated during initial substrate preorganization step, oxidosqualene cyclases （OSCs） are roughly segregated into protosteryl cation group that mainly catalyzes tetracyclic products and dammarenyl cation group which mostly generates pentacyclic products. However, in contrast to well-studied cascade of ring-forming reactions, little is known about the mechanism underlying the initial sub- strate folding process. Previously, we have identified a cucurbitadienol synthase （Bi） and its null allele bi （C393Y） from cucumber. By integration of homology modeling, residue coevolution and site-directed mutagenesis, we discover that four covarying amino acids including C393 constitute a dynamic domain that may be involved in substrate folding process for Bi. We also reveal a group of co-conserved residues that closely associated with the segregation of plant OSCs. These residues may act col- laboratively in choice of specific substrate folding inter- mediate for OSCs. Thus, engineer plant OSCs from into five-ringed producer. our findings open a door to four-ringed skeleton catalystsSterols and triterpenes are structurally diverse bioactive molecules generated through cyclization of linear2,3-oxidosqualene. Based on carbocationic intermediates generated during initial substrate preorganization step,oxidosqualene cyclases(OSCs) are roughly segregated into protosteryl cation group that mainly catalyzes tetracyclic products and dammarenyl cation group which mostly generates pentacyclic products. However, in contrast to well-studied cascade of ring-forming reactions, little is known about the mechanism underlying the initial substrate folding process. Previously, we have identified a cucurbitadienol synthase(Bi) and its null allele bi(C393Y)from cucumber. By integration of homology modeling,residue coevolution and site-directed mutagenesis, we discover that four covarying amino acids including C393 constitute a dynamic domain that may be involved in substrate folding process for Bi. We also reveal a group of co-conserved residues that closely associated with the segregation of plant OSCs. These residues may act collaboratively in choice of specific substrate folding intermediate for OSCs. Thus, our findings open a door to engineer plant OSCs from four-ringed skeleton catalysts into five-ringed producer.

关 键 词：Oxidosqualene cyclase Homologymodeling Residue coevolution Substrate folding 

分 类 号：O629[理学—有机化学]