Protein glycation in vivo: functional and structural effects on yeast enolase.
Protein glycation is involved in structure and stability changes that impair protein functionality, which is associated with several human diseases, such as diabetes and amyloidotic neuropathies (Alzheimer's disease, Parkinson's disease and Andrade's syndrome). To understand the relationship of protein glycation with protein dysfunction, unfolding and beta-fibre formation, numerous studies have been carried out in vitro. All of these previous experiments were conducted in non-physiological or pseudo-physiological conditions that bear little to no resemblance to what may happen in a living cell. In vivo, glycation occurs in a crowded and organized environment, where proteins are exposed to a steady-state of glycation agents, namely methylglyoxal, whereas in vitro, a bolus of a suitable glycation agent is added to diluted protein samples. In the present study, yeast was shown to be an ideal model to investigate glycation in vivo since it shows different glycation phenotypes and presents specific protein glycation targets. A comparison between in vivo glycated enolase and purified enolase glycated in vitro revealed marked differences. All effects regarding structure and stability changes were enhanced when the protein was glycated in vitro. The same applies to enzyme activity loss, dimer dissociation and unfolding. However, the major difference lies in the nature and location of specific advanced glycation end-products. In vivo, glycation appears to be a specific process, where the same residues are consistently modified in the same way, whereas in vitro several residues are modified with different advanced glycation end-products.
Gomes
Ricardo A
RA
Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, Edifício C8, 1749-016 Lisboa, Portugal.
Oliveira
Luís M A
LM
Silva
Mariana
M
Ascenso
Carla
C
Quintas
Alexandre
A
Costa
Gonçalo
G
Coelho
Ana V
AV
Sousa Silva
Marta
M
Ferreira
António E N
AE
Ponces Freire
Ana
A
Cordeiro
Carlos
C
D000595:Amino Acid Sequence; D001120:Arginine / Q000378:metabolism; D004795:Enzyme Stability; D017127:Glycation End Products, Advanced / Q000737:chemistry / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010751:Phosphopyruvate Hydratase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D017127:Glycation End Products, Advanced; D029701:Saccharomyces cerevisiae Proteins; D001120:Arginine; D010751:Phosphopyruvate Hydratase