A novel alcohol dehydrogenase in the hyperthermophilic crenarchaeon Hyperthermus butylicus  

作　　者：Ching Tse Kesen Ma 

机构地区：[1]Department of Biology,University of Waterloo,Waterloo,Ontario,Canada

出　　处：《mLife》2024年第2期317-325,共9页微生物（英文）

基　　金：supported by a research grant from the Natural Sciences and Engineering Research Council of Canada(NSERC)to K.M.

摘　　要：Hyperthermus butylicus is a hyperthermophilic crenarchaeon that produces 1-butanol as an end product.A thermostable alcohol dehydrogenase(ADH)must be present in H.butylicus to act as the key enzyme responsible for this production;however,the gene that encodes the ADH has not yet been identified.A novel ADH,HbADH2,was purified from a cell-free extract of H.butylicus,and its characteristics were determined.The gene that encodes HbADH2 was demonstrated to be HBUT_RS04850 and annotated as a hypothetical protein in H.butylicus.HbADH2 was found to be a primary-secondary ADH capable of using a wide range of substrates,including butyraldehyde and butanol.Butyraldehyde had the highest specificity constant,calculated as k_(cat)/K_(m),with kcat and apparent K_(m) values of 8.00±0.22 s^(-1) and 0.59±0.07 mM,respectively.The apparent Km values for other substrates,including ethanol,1-propanol,2-propanol,butanol,acetaldehyde,propanal,and acetone,were 4.36±0.42,4.69±0.41,3.74±0.46,2.44±0.30,1.27±0.18,1.55±0.20,and 0.68±0.04 mM,respectively.The optimal pH values for catalyzing aldehyde reduction and alcohol oxidation were 6.0 and 9.0,respectively,while the optimal temperature was higher than 90°C due to the increase in enzymatic activity from 60℃ to 90℃.Based on its substrate specificity,enzyme kinetics,and thermostability,HbADH2 may be the ADH that catalyzes the production of 1-butanol in H.butylicus.The putative conserved motif sites for NAD(P)^(+)and iron binding were identified by aligning HbADH2 with previously characterized Fe-containing ADHs.

关 键 词：BUTANOL HYPERTHERMOPHILE Hyperthermus butylicus novel alcohol dehydrogenase thermostability 

分 类 号：Q93[生物学—微生物学]