NADP-malic enzyme and Hsp70: co-purification of both proteins and modification of NADP-malic enzyme properties by association with Hsp70

LARA, MARIA V.; DRINCOVICH, MARÍA F.; MÜLLER, GABRIELA L.; MAURINO, VERÓNICA G.; ANDREO, CARLOS S.

PLANT AND CELL PHYSIOLOGY

OXFORD UNIV PRESS

Año: 2005 vol. 46 p. 997 - 1006

0032-0781

Different preparations of antibodies against 62 kDaNADP-malic enzyme (NADP-ME) from purified maizeleaves cross-react with a 72 kDa protein from diverse tissuesin many species. A 72 kDa protein, suggested to be anon-photosynthetic NADP-ME, has been purified from severalplant species. However, to date, a cDNA coding for thisputative 72 kDa NADP-ME has not been isolated. Thescreening of maize and tobacco leaf expression librariesusing antibodies against purified 62 kDa NADP-ME allowedthe identification of a heat shock protein (Hsp70). In addition,tandem mass spectrometry (MS/MS) studies indicatethat along with NADP-ME, a 72 kDa protein, identified asan Hsp70 and reacting with the antibodies, is also purifiedfrom maize roots. On the other hand, the screening of amaize root cDNA library revealed the existence of a cDNAthat encodes a mature 66 kDa NADP-ME. These resultssuggest that the 72 kDa protein is not actually an NADPMEbut in fact an Hsp70, at least in maize and tobacco.Probably, NADP-ME?Hsp70 association, taking place atleast when preparing crude extracts, can lead to a copurificationof the proteins and can thus explain the crossreactionof the antibodies. In the present work, we analyseand discuss a probable interaction of NADP-ME withHsp70.