Two Malic Enzymes in Pseudomonas aeruginosa

Abstract

Cell-free extract supematant fluids of Pseudomonas aeruginosa were shown to lack malic dehydrogenase but possess a nicotinamide adenine dinucleotide (NAD)or NAD phosphate (NADP)-dependent enzymatic activity, with properties suggesting a malic enzyme (malate + NAD (NADP)-_ pyruvate + reduced NAD (NADH) (reduced NADP [NADPH] + C02), in agreement with earlier findings. This was confirmed by determining the nature and stoichiometry of the reaction products. Differences in heat stability and partial purification of these activities demonstrated the existence of two malic enzymes, one specific for NAD and the other for NADP. Both enzymes require bivalent metal cations for activity, Mn2+ being more effective than Mg2+. The NADP-dependent enzyme is activated by K+ and low concentrations of NH,+. Both reactions are reversible, as shown by incubation with pyruvate, C02, NADH, or NADPH and Mn2+. The molecular weights of the enzymes were estimated by gel filtration (270,000 for the NAD enzyme and 68,000 for the NADP enzyme) and by sucrose density gradient centrifugation (about 200,000 and 90,000, respectively).

Manganese transport is essential for N2‐fixation by Rhizobium leguminosarum in bacteroids from galegoid but not phaseoloid nodules

“…The symbiotic requirement of Mn 21 cannot therefore be completely attributed to SodA and instead may also reflect its ability to replace Fe 21 as a cofactor under oxidative stress (Anjem et al, 2009). Alternatively, the requirement of Mn 21 may not be restricted to oxidative stress resistance as some bacteria utilise the metal as a cofactor for enzymes central to metabolism (Eyzaguir et al, 1973;Hohle and O'Brian, 2012).…”

Pyruvate Carboxylase Deficiency in Pleiotropic Carbohydrate-Negative Mutant Strains of Pseudomonas aeruginosa

“…Both NADand NADP-dependent malic enzymes (EC 1.1.1.39 and EC 1.1.1.40, respectively) have been reported in several species of Pseudomonas, including P. aeruginosa (9,17).…”

The PEP—pyruvate—oxaloacetate node as the switch point for carbon flux distribution in bacteria: We dedicate this paper to Rudolf K. Thauer, Director of the Max-Planck-Institute for Terrestrial Microbiology in Marburg, Germany, on the occasion of his 65th birthday

“…Most organisms possess an NADP-dependent malic enzyme, some bacteria such as E. coli and other enteric bacteria, B. subtilis, Rhizobium sp., Pseudomonas sp., Alcaligines faecalis, and Agrobacterium tumefaciens possess both (an) NAD-and an NADP-specific enzyme(s) (e.g. [60,67,[103][104][105][106]). Lactic acid bacteria possess NADlinked malic enzymes of the EC 1.1.1.39-type [107][108][109][110].…”