Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 3 de 3
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
Artículo en Inglés | MEDLINE | ID: mdl-18852060

RESUMEN

Annelids as a group express a variety of phosphagen kinases including creatine kinase (CK), glyocyamine kinase (GK), lombricine kinase (LK), taurocyamine kinase (TK) and a unique arginine kinase (AK) restricted to annelids. In prior work, we have determined and compared the intron/exon organization of the annelid genes for cytoplasmic GK, LK, AK, and mitochondrial TK and LK (MiTK and MiLK, respectively), and found that these annelid genes, irrespective of cytoplasmic or mitochondrial, have the same 8-intron/9-exon organization strikingly similar to mitochondrial CK (MiCK) genes. These results support the view that the MiCK gene is basal and ancestral to the phosphagen kinases unique to annelids. To gain a greater understanding of the evolutionary processes leading to the diversity of annelid phosphagen kinases, we determined for the first time the intron/exon organization of a cytoplasmic CK gene from a polychaete as well as that of another polychaete MiCK gene. These gene structures, coupled with a phylogenetic analyses of annelid enzymes and assessment of the fidelity of substrate specificity of some these phosphagen kinases, provide insight into the pattern of radiation of the annelid enzymes. Annelid phosphagen kinases appeared to have diverged in the following order (earliest first): (1) cytoplasmic AK, LK and TK, (2) GK, and (3) mitochondrial MiLK and MiTK. Interestingly, phylogenetic analyses showed that the above phosphagen kinases appear to be basal to all CK isoforms (mitochondrial, cytoplasmic and flagellar CKs). This somewhat paradoxical placement of CKs most likely reflects a higher rate of evolution and radiation of the annelid-specific LK, TK and GK genes than the CK isoform genes.


Asunto(s)
Anélidos/enzimología , Creatina Quinasa/genética , Evolución Molecular , Animales , Citoplasma/enzimología , Exones , Intrones , Proteínas Mitocondriales , Fosfotransferasas (Aceptor del Grupo Nitrogenado)/genética , Isoformas de Proteínas/genética , Especificidad por Sustrato
2.
Comp Biochem Physiol B Biochem Mol Biol ; 140(3): 387-93, 2005 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-15694586

RESUMEN

We isolated cytoplasmic glycocyamine kinase (GK) and creatine kinase (CK) from the tropical marine worm Namalycastis sp. by ammonium sulfate fractionation, gel filtration on Sephacryl S-200, and DEAE-5PW chromatography. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that the isolated GK is highly purified and appears to be a heterodimer of two distinct subunits, alpha and beta, with molecular masses of approximately 40 kDa. The complete nucleotide sequences of the cDNAs for Namalycastis GKalpha and GKbeta were 1527 (encoding 374 amino acids) and 1579 bp (encoding 390 amino acids), respectively. The predicted amino acid sequences differ only in the N-terminal 50 residues. This is consistent with the characteristics of Neanthes GKalpha and GKbeta chains, which we have previously shown to be generated by alternative splicing. The recombinant enzymes GKalpha, GKbeta, and CK from Namalycastis were successfully expressed in Escherichia coli as maltose-binding protein fusion proteins. In contrast to the stable GKbeta enzyme, GKalpha was quite unstable, and its activity decreased remarkably with time. Thus, the N-terminal 50 residues appear to play a key role in enzyme stability. The kinetic parameters for the native GK heterodimer were similar to GKbeta, suggesting that GKalpha would have an activity similar to GKbeta if part of a heterodimer. This is the first report of precise kinetic parameters for GK. Finally, based on our results, we present a model for pluriphosphagen function in Namalycastis wherein cytoplasmic GK and CK and mitochondrial CK function together with phosphocreatine and phosphoglycocyamine to enable cells to respond quickly to a sudden large energy requirement.


Asunto(s)
Fosfotransferasas (Aceptor del Grupo Nitrogenado)/química , Poliquetos/enzimología , Secuencia de Aminoácidos , Animales , Clonación Molecular , Creatina Quinasa/química , Creatina Quinasa/genética , Creatina Quinasa/aislamiento & purificación , ADN Complementario/genética , Escherichia coli/enzimología , Escherichia coli/genética , Datos de Secuencia Molecular , Fosfotransferasas (Aceptor del Grupo Nitrogenado)/genética , Fosfotransferasas (Aceptor del Grupo Nitrogenado)/aislamiento & purificación , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo
3.
J Mol Evol ; 59(2): 218-26, 2004 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-15486695

RESUMEN

Creatine kinase (CK) plays a central role in energy homeostasis in cells that display high and variable rates of energy turnover. A number of CK genes exist, each being targeted to particular intracellular compartments. In the vertebrates, two genes code for proteins which form homo- and heterodimers targeted to the cytoplasm, while two additional genes code for primarily octameric proteins targeted to the mitochondrial intermembrane space. Yet another gene is present in certain groups which codes for three fused, complete CK domains and is typically targeted to the flagellar membrane of primitive-type spermatozoa. CK is widely distributed in protochordates and both protostome and deuterostome invertebrate groups. The evolutionary relationships of these CK genes have not been fully elucidated. The present communication reports new cDNA-derived deduced amino acid sequences for four cytoplasmic and three mitochondrial CKs and one flagellar CK from lophotrochozoan, protostome invertebrates as well as a new cytoplasmic CK sequence from a protochordate tunicate. These new sequences, coupled with available sequences in the databases and sequences extracted from genome sequencing projects, provide revealing insights into the evolution and divergence of CK genes. Phylogenetic analyses showed that single cytoplasmic, mitochondrial, and flagellar CK genes were present prior to the divergence of the protostomes and deuterostomes. The flagellar CK gene may have evolved within the cytoplasmic gene clade, although the evidence is somewhat equivocal. The two cytoplasmic genes in the vertebrates, and most likely the two mitochondrial genes, evolved after the divergence of the craniates from the protochordates. Comparison of the structure of the genes for selected cytoplasmic, mitochondrial, and flagellar CKs revealed two identical intron boundaries, further reinforcing the notion of a common evolutionary origin, but also showed patterns of changes in structure consistent with each gene type. These studies show that the cytoplasmic, mitochondrial, and flagellar CK genes are rather ancient and that there has been a systematic pattern of duplication and divergence consistent with changing nature of energy demands and physicochemical environment in the cells where they are expressed.


Asunto(s)
Creatina Quinasa/genética , Evolución Molecular , Variación Genética , Invertebrados/genética , Filogenia , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Citoplasma/genética , Citoplasma/metabolismo , ADN Complementario/genética , Flagelos/genética , Flagelos/metabolismo , Componentes del Gen , Funciones de Verosimilitud , Mitocondrias/genética , Mitocondrias/metabolismo , Modelos Genéticos , Datos de Secuencia Molecular , Técnicas de Amplificación de Ácido Nucleico , Alineación de Secuencia , Análisis de Secuencia de ADN
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA