SELECTIVE PROTEOLYSIS OF THE PROTEIN-X SUBUNIT OF THE BOVINE HEART PYRUVATE-DEHYDROGENASE COMPLEX - EFFECTS ON DIHYDROLIPOAMIDE DEHYDROGENASE (E3) AFFINITY AND ENZYMATIC-PROPERTIES OF THE COMPLEX

被引:34
作者
NEAGLE, JC [1 ]
LINDSAY, JG [1 ]
机构
[1] UNIV GLASGOW, DEPT BIOCHEM, GLASGOW G12 8QQ, SCOTLAND
关键词
D O I
10.1042/bj2780423
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Selective proteolysis of the protein X subunit of native bovine heart pyruvate dehydrogenase complex may be accomplished without loss of overall complex activity. Partial loss of function occurs if Mg2+ and thiamin pyrophosphate are not present during proteinase arg C treatment as these cofactors are necessary to prevent cleavage of the E1-alpha subunit. Specific degradation of component X leads to marked alterations in the general enzymic properties of the complex. Lipoamide dehydrogenase (E3) exhibits a decreased affinity for the core assembly and the complex is much more susceptible to inactivation at high ionic strength. The inactive form of the complex is not readily re-activated by removal of salt. It appears that intact protein X and specifically the presence of its cleaved lipoyl domain is not essential for maintenance of an enzymically active pyruvate dehydrogenase complex. However, this protein has an important structural role in promoting the correct association of E3 with the E2 core assembly, an interaction that is required for optimal catalytic efficiency of the complex.
引用
收藏
页码:423 / 427
页数:5
相关论文
共 18 条
[1]   CLONING AND NUCLEOTIDE-SEQUENCE OF THE GENE FOR PROTEIN-X FROM SACCHAROMYCES-CEREVISIAE [J].
BEHAL, RH ;
BROWNING, KS ;
HALL, TB ;
REED, LJ .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1989, 86 (22) :8732-8736
[2]   COMPONENT-X - AN IMMUNOLOGICALLY DISTINCT POLYPEPTIDE ASSOCIATED WITH MAMMALIAN PYRUVATE-DEHYDROGENASE MULTI-ENZYME COMPLEX [J].
DEMARCUCCI, O ;
LINDSAY, JG .
EUROPEAN JOURNAL OF BIOCHEMISTRY, 1985, 149 (03) :641-648
[3]  
DEMARCUCCI OGL, 1986, EUR J BIOCHEM, V158, P587
[4]   LOW IMMUNOGENICITY OF THE COMMON LIPOAMIDE DEHYDROGENASE SUBUNIT (E3) OF MAMMALIAN PYRUVATE-DEHYDROGENASE AND 2-OXOGLUTARATE DEHYDROGENASE MULTIENZYME COMPLEXES [J].
DEMARCUCCI, OL ;
HUNTER, A ;
LINDSAY, JG .
BIOCHEMICAL JOURNAL, 1985, 226 (02) :509-517
[5]   ROLE OF PROTEIN-X IN THE FUNCTION OF THE MAMMALIAN PYRUVATE-DEHYDROGENASE COMPLEX [J].
GOPALAKRISHNAN, S ;
RAHMATULLAH, M ;
RADKE, GA ;
POWERSGREENWOOD, S ;
ROCHE, TE .
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 1989, 160 (02) :715-721
[6]   LIPOIC ACID IS THE SITE OF SUBSTRATE-DEPENDENT ACETYLATION OF COMPONENT-X IN OX HEART PYRUVATE-DEHYDROGENASE MULTIENZYME COMPLEX [J].
HODGSON, JA ;
DEMARCUCCI, OG ;
LINDSAY, JG .
EUROPEAN JOURNAL OF BIOCHEMISTRY, 1986, 158 (03) :595-600
[7]   IMMUNOLOGICAL AND BIOSYNTHETIC-STUDIES ON THE MAMMALIAN 2-OXOGLUTARATE DEHYDROGENASE MULTIENZYME COMPLEX [J].
HUNTER, A ;
LINDSAY, JG .
EUROPEAN JOURNAL OF BIOCHEMISTRY, 1986, 155 (01) :103-109
[8]  
JILKA JM, 1986, J BIOL CHEM, V261, P1858
[9]   DISRUPTION AND MUTAGENESIS OF THE SACCHAROMYCES-CEREVISIAE PDX1 GENE ENCODING THE PROTEIN-X COMPONENT OF THE PYRUVATE-DEHYDROGENASE COMPLEX [J].
LAWSON, JE ;
BEHAL, RH ;
REED, LJ .
BIOCHEMISTRY, 1991, 30 (11) :2834-2839
[10]   COMPONENT-X OF MAMMALIAN PYRUVATE-DEHYDROGENASE COMPLEX - STRUCTURAL AND FUNCTIONAL-RELATIONSHIP TO THE LIPOATE ACETYLTRANSFERASE (E2) COMPONENT [J].
NEAGLE, J ;
DEMARCUCCI, O ;
DUNBAR, B ;
LINDSAY, JG .
FEBS LETTERS, 1989, 253 (1-2) :11-15