Testis-specific glyceraldehyde-3-phosphate dehydrogenase: origin and evolution

<p>Abstract</p> <p>Background</p> <p>Glyceraldehyde-3-phosphate dehydrogenase (GAPD) catalyses one of the glycolytic reactions and is also involved in a number of non-glycolytic processes, such as endocytosis, DNA excision repair, and induction of apoptosis. Mammals are known to possess two homologous GAPD isoenzymes: GAPD-1, a well-studied protein found in all somatic cells, and GAPD-2, which is expressed solely in testis. GAPD-2 supplies energy required for the movement of spermatozoa and is tightly bound to the sperm tail cytoskeleton by the additional N-terminal proline-rich domain absent in GAPD-1. In this study we investigate the evolutionary history of GAPD and gain some insights into specialization of GAPD-2 as a testis-specific protein.</p> <p>Results</p> <p>A dataset of GAPD sequences was assembled from public databases and used for phylogeny reconstruction by means of the Bayesian method. Since resolution in some clades of the obtained tree was too low, syntenic analysis was carried out to define the evolutionary history of GAPD more precisely. The performed selection tests showed that selective pressure varies across lineages and isoenzymes, as well as across different regions of the same sequences.</p> <p>Conclusions</p> <p>The obtained results suggest that GAPD-1 and GAPD-2 emerged after duplication during the early evolution of chordates. GAPD-2 was subsequently lost by most lineages except lizards, mammals, as well as cartilaginous and bony fishes. In reptilians and mammals, GAPD-2 specialized to a testis-specific protein and acquired the novel N-terminal proline-rich domain anchoring the protein in the sperm tail cytoskeleton. This domain is likely to have originated by exonization of a microsatellite genomic region. Recognition of the proline-rich domain by cytoskeletal proteins seems to be unspecific. Besides testis, GAPD-2 of lizards was also found in some regenerating tissues, but it lacks the proline-rich domain due to tissue-specific alternative splicing.</p

Interactions between abscisic acid and plastidial glycolysis in Arabidopsis

The phytohormone abscisic acid (ABA) controls the development of plants and plays a crucial role in their response to adverse environmental conditions like salt and water stress.1–3 Complex interactions between ABA and sugar signal transduction pathways have been shown. However, the role played by glycolysis in these interactions is not known. In the associated study,4 we investigated the interactions between plastidial glycolytic glyceraldehyde-3-phosphate dehydrogenase (GAPCp) and ABA signal transduction in Arabidopsis. We followed physiological, genetic and genomic approaches to understand the processes and mechanisms underlying the ABA-glycolysis interactions. Our results indicated that GAPCp deficiency leads to ABA-insensitivity and impaired ABA signal transduction. The gene expression of the transcription factor ABI4, involved in both sugar and ABA signaling, was altered in gapcp double mutants (gapcp1gapcp2), suggesting that the ABA insensitivity of mutants is mediated, at least in part, through this transcriptional regulator. We also suggested that amino acid homeostasis and/or serine metabolism may also be important determinants in the connections of ABA with primary metabolism. These studies provide new insights into the links between plant primary metabolism and ABA signal transduction, and demonstrate the importance of plastidial glycolytic GAPCps in these interactions

Glyceraldehyde 3-Phosphate Dehydrogenase-Telomere Association Correlates with Redox Status in Trypanosoma cruzi

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is a classical metabolic enzyme involved in energy production and plays a role in additional nuclear functions, including transcriptional control, recognition of misincorporated nucleotides in DNA and maintenance of telomere structure. Here, we show that the recombinant protein T. cruzi GAPDH (rTcGAPDH) binds single-stranded telomeric DNA. We demonstrate that the binding of GAPDH to telomeric DNA correlates with the balance between oxidized and reduced forms of nicotinamide adenine dinucleotides (NAD+/NADH). We observed that GAPDH-telomere association and NAD+/NADH balance changed throughout the T. cruzi life cycle. For example, in replicative epimastigote forms of T. cruzi, which show similar intracellular concentrations of NAD+ and NADH, GAPDH binds to telomeric DNA in vivo and this binding activity is inhibited by exogenous NAD+. In contrast, in the T. cruzi non-proliferative trypomastigote forms, which show higher NAD+ concentration, GAPDH was absent from telomeres. In addition, NAD+ abolishes physical interaction between recombinant GAPDH and synthetic telomere oligonucleotide in a cell free system, mimicking exogenous NAD+ that reduces GAPDH-telomere interaction in vivo. We propose that the balance in the NAD+/NADH ratio during T. cruzi life cycle homeostatically regulates GAPDH telomere association, suggesting that in trypanosomes redox status locally modulates GAPDH association with telomeric DNA.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Inst Butantan, Lab Especial Ciclo Celular, Sao Paulo, BrazilInst Butantan, Ctr Toxins Immune Response &Cell Signaling CeTIC, Sao Paulo, BrazilUniv Sao Paulo, Inst Ciencias Biomed, Dept Parasitol, Unit Drug Discovery, BR-05508 Sao Paulo, BrazilUniv Sao Paulo, Inst Quim, Dept Bioquim, BR-01498 Sao Paulo, BrazilUniv Estadual Paulista Julio de Mesquita Filho UN, Inst Biociencias, Dept Genet, Botucatu, SP, BrazilUniv Estadual Paulista Julio de Mesquita Filho UN, Inst Biociencias, Dept Genet, Botucatu, SP, BrazilFAPESP: 2005/00154-1FAPESP: 2013/07467-1FAPESP: 2011/50631-