A Preliminary Study On The Expression And Function Of Maize Enolase

Enolase is an important enzyme in both glycolytic and gluconeogenesis pathways.In glycolysis,the enzyme catalyzes the conversion of2-phosphoglycerate(2-PGA)to phosphoenolpyruvate(PEP),the only dehydration step in this pathway,providing the energy and material guarantee for the final product pyruvate.The phosphorylation of 2-PGA is occurring at the substrate level.In gluconeogenesis pathway,the enzyme catalyzes the conversion of PEP to 2-PGA.The enzyme exists in the dimer form.Amino acid sequences are highly conserved,sequence homology was higher among different species.In recent years,study showed that the enzyme not only play a catalytic role in the process of glucose metabolism,but also involved in the response to some stresses in plants.There are nine kinds of enolase in maize,while the study about them is poor.In this study,we compared the specificity expression of the enzyme in root,coleoptile,pollen,embryo,filaments,young leaves,mature leaves via the enolase antibody,and further analyzed of the changes in of the enzyme the in response to in low temperature,drought treatment.Results are as following:(1)The expression of enolase in different tissues is different.Through RT-PCR analysis,we found that the difference of the enzyme gene expression in these tissues is not big.The enzyme protein expression in roots was the highest,followed by pollen and coleoptile;in the embryo,filaments,young leaves,mature leaves the expression is relatively low by Western blotting.This is mainly due to the energy for the activities of non green tissues,such as root absorption of nutrients,maturation of the pollen,in photosynthetic plants is mostly provided by glycolysis.(2)Choose root,coleoptile as materials,by 2-DE,Western blotting and mass spectrometry,we found the enzyme display two different protein isoforms in maize.The isoforms have the same molecular weight but different isoelectric points,which may is the result of post-translational modification.(3)2-DE analysis and RT-PCR showed that the abundance of the two isoforms were increased under low temperature and drought stresses.At the same time,the enzyme gene expression was also increased.However,under drought stress,the expression of the gene and the protein was higher than that under low temperature stress,which may be due to the dehydration reaction of the enzyme catalyzed by the enzyme.By bioinformatics analysis,we found that the enzyme is a transmembrane protein,it may be involved in the signal transduction of stress.These results indicated that the enzyme could be induced by drought and low temperature stresses,and played a role in the mechanism of response to stress.These laid a certain foundation for further research on the function of maize enolase.