Molecular genetics of the maize (Zea mays L.) aspartate kinase-homoserine dehydrogenase gene family

G. J. Muehlbauer, D. A. Somers, B. F. Matthews, B. G. Gengenbach

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Aspartate kinase (AK) and homoserine dehydrogenase (HSDH) are enzymes in the aspartate-derived amino acid biosynthetic pathway. Recent biochemical evidence indicates that an AK-HSDH bifunctional enzyme exists in maize (Zea mays L). In this report, we characterize three genes that encode subunits of AK-HSDH. Two cDNAs, pAKHSDH1 and pAKHSDH2, containing the full-coding sequence, and one partial cDNA, pAKHSDH3, encode amino acid sequences similar to the reported monofunctional AK and HSDH enzymes from prokaryotes and yeast (Saccharomyces cerevisiae) and to AK-HSDH bifunctional enzymes of prokaryotes, yeast, carrot (Daucus carota), and Arabidopsis thaliana. Immunological and biochemical analyses verify that the cDNAs encode AK-HSDH and indicate that both the AK and HSDH activities are feedback inhibited by threonine. RNA blots identify a 3.2-kb transcript in all maize tissues examined. pAKHSDH1 and pAKHSDH2 map to chromosomes 4L and 2S, respectively. This study shows that maize contains AK-HSDH bifunctional enzyme(s) encoded by a small gene family of at least three genes. Maize AK-HSDH has conserved sequences found in communication modules of prokaryotic two-component regulatory systems, which has led us to propose that maize AK-HSDH may be involved in a similar regulatory mechanism.

Original languageEnglish (US)
Pages (from-to)1303-1312
Number of pages10
JournalPlant physiology
Issue number4
StatePublished - Dec 1994


Dive into the research topics of 'Molecular genetics of the maize (Zea mays L.) aspartate kinase-homoserine dehydrogenase gene family'. Together they form a unique fingerprint.

Cite this