Is 2-phosphoglycerate-dependent automodification of bacterial enolases implicated in their export?
We observed that in vivo and in vitro a small fraction of the glycolytic enzyme enolase became covalently modified by its substrate 2-phosphoglycerate (2-PG). In modified Escherichia coli enolase, 2-PG was bound to Lys341, which is located in the active site. An identical reversible modification was observed with other bacterial enolases, but also with enolase from Saccharomyces cerevisiae and rabbit muscle. An equivalent of Lys341, which plays an important role in catalysis, is present in enolase of all organisms. Covalent binding of 2-PG to this amino acid rendered the enzyme inactive. Replacement of Lys341 of E.coli enolase with other amino acids prevented the automodification and in most cases strongly reduced the activity. As reported for other bacteria, a significant fraction of E.coli enolase was found to be exported into the medium. Interestingly, all Lys341 substitutions prevented not only the automodification, but also the export of enolase. The K341E mutant enolase was almost as active as the wild-type enzyme and therefore allowed us to establish that the loss of enolase export correlates with the loss of modification and not the loss of glycolytic activity.
Boël
Grégory
G
Microbiologie et Génétique Moléculaire, CNRS/INRA/INA-PG, UMR 2585, F-78850, Thiverval-Grignon, France.
Pichereau
Vianney
V
Mijakovic
Ivan
I
Mazé
Alain
A
Poncet
Sandrine
S
Gillet
Sylvie
S
Giard
Jean-Christophe
JC
Hartke
Axel
A
Auffray
Yanick
Y
Deutscher
Josef
J
D000818:Animals; D001419:Bacteria / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D001693:Biological Transport, Active; D020134:Catalytic Domain / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D013293:Enterococcus faecalis / Q000201:enzymology / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005798:Genes, Bacterial; D005988:Glyceric Acids / Q000378:metabolism*; D066298:In Vitro Techniques; D008239:Lysine / Q000737:chemistry; D016297:Mutagenesis, Site-Directed; D010728:Phosphoenolpyruvate / Q000378:metabolism; D010751:Phosphopyruvate Hydratase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011817:Rabbits; D012441:Saccharomyces cerevisiae / Q000201:enzymology
D004269:DNA, Bacterial; D005988:Glyceric Acids; C008885:2-phosphoglycerate; D010728:Phosphoenolpyruvate; D010751:Phosphopyruvate Hydratase; D008239:Lysine