Malate, Aspartate and Proton Exchange Between Rhizobium Leguminosarvm Symbiosomes and Its Symbiotic Partner Pisum Sativum.

Haaker, H.; Szafran, M.; Wassink, Hans; Appels, Michiel A.

doi:10.1007/978-94-011-0379-4_67

Cited by 5 publications

(1 citation statement)

References 9 publications

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“…Immunological studies of yellow lupine using a mixed population of antibodies demonstrated that root nodules contain novel forms of MDH (Ratajczak et al, 1989). Haaker et al (1995) and Appels and Haaker (1988) reported that effective pea nodules contained a unique nodule-enhanced form of MDH. However, neMDH has not been isolated and characterized and there has been only one brief report of the cloning of a plant cytosolic MDH (Ocheretina and Scheibe, 1997).…”

Section: Introductionmentioning

confidence: 99%

Alfalfa malate dehydrogenase (MDH): molecular cloning and characterization of five different forms reveals a unique nodule‐enhanced MDH

Miller¹,

Driscoll²,

Gregerson³

et al. 1998

The Plant Journal

153

100

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SummaryMalate dehydrogenase (MDH) catalyzes the readily reversible reaction of oxaloacetate ≤ malate using either NADH or NADPH as a reductant. In plants, the enzyme is important in providing malate for C 4 metabolism, pH balance, stomatal and pulvinal movement, respiration, β-oxidation of fatty acids, and legume root nodule functioning. Due to its diverse roles the enzyme occurs as numerous isozymes in various organelles. While antibodies have been produced and cDNAs characterized for plant mitochondrial, glyoxysomal, and chloroplast forms of MDH, little is known of other forms. Here we report the cloning and characterization of cDNAs encoding five different forms of alfalfa MDH, including a plant cytosolic MDH (cMDH) and a unique novel nodule-enhanced MDH (neMDH). Phylogenetic analyses show that neMDH is related to mitochondrial and glyoxysomal MDHs, but diverge from these forms early in land plant evolution. Four of the five forms could effectively complement an E. coli Mdh -mutant. RNA and protein blots show that neMDH is most highly expressed in effective root nodules. Immunoprecipitation experiments show that antibodies produced to cMDH and neMDH are immunologically distinct and that the neMDH form comprises the major form of total MDH activity and protein in root nodules. Kinetic analysis showed that neMDH has a turnover rate and specificity constant that can account for the extraordinarily high synthesis of malate in nodules.

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