Catalytic mechanism of the adenylyl and guanylyl cyclases: Modeling and mutational analysis
AUTOR(ES)
Liu, Yu
FONTE
The National Academy of Sciences of the USA
RESUMO
The adenylyl and guanylyl cyclases catalyze the formation of 3′,5′-cyclic adenosine or guanosine monophosphate from the corresponding nucleoside 5′-triphosphate. The guanylyl cyclases, the mammalian adenylyl cyclases, and their microbial homologues function as pairs of homologous catalytic domains. The crystal structure of the rat type II adenylyl cyclase C2 catalytic domain was used to model by homology a mammalian adenylyl cyclase C1-C2 domain pair, a homodimeric adenylyl cyclase of Dictyostelium discoideum, a heterodimeric soluble guanylyl cyclase, and a homodimeric membrane guanylyl cyclase. Mg2+ATP or Mg2+GTP were docked into the active sites based on known stereochemical constraints on their conformation. The models are consistent with the activities of seven active-site mutants. Asp-310 and Glu-432 of type I adenylyl cyclase coordinate a Mg2+ ion. The D310S and D310A mutants have 10-fold reduced Vmax and altered [Mg2+] dependence. The NTP purine moieties bind in mostly hydrophobic pockets. Specificity is conferred by a Lys and an Asp in adenylyl cyclase, and a Glu, an Arg, and a Cys in guanylyl cyclase. The models predict that an Asp from one domain is a general base in the reaction, and that the transition state is stabilized by a conserved Asn-Arg pair on the other domain.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=28319Documentos Relacionados
- Origin of asymmetry in adenylyl cyclases: structures of Mycobacterium tuberculosis Rv1900c
- The Linker Region in Receptor Guanylyl Cyclases Is a Key Regulatory Module: MUTATIONAL ANALYSIS OF GUANYLYL CYCLASE C*
- Receptor guanylyl cyclases.
- Mutational analysis of the damage-recognition and catalytic mechanism of human SMUG1 DNA glycosylase
- Adenylyl cyclase Rv1625c of Mycobacterium tuberculosis: a progenitor of mammalian adenylyl cyclases