ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS Vol. 337, No. 1, January 1, pp. 81–88, 1997 Article No. BB969731 Betaine-Aldehyde Dehydrogenase from Amaranth Leaves Efficiently Catalyzes the NAD-Dependent Oxidation of Dimethylsulfoniopropionaldehyde to Dimethylsulfoniopropionate 1 Martina Vojte ˇchova ´ ,* Andrew D. Hanson,† ,2 and Rosario A. Mun ˜ oz-Clares* ,3 *Departamento de Bioquı B mica, Facultad de Quı B mica, Universidad Nacional Auto ´noma de Me ´xico, Me ´xico D.F. 04510, Me ´xico; and †Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611-0690 Received June 17, 1996, and in revised form September 9, 1996 simply have been recruited for a novel function.  1997 Academic Press, Inc. Many flowering plants accumulate the compatible Key Words: 3-Dimethylsulfoniopropionaldehyde osmolyte glycine betaine in response to osmotic stress, oxidation; betaine-aldehyde dehydrogenase; kinetic in certain cases together with its sulfonium analog 3- mechanism; 3-dimethylsulfoniopropionate; Amaran- dimethylsulfoniopropionate (DMSP). Compared to thus hypochondriacus L. glycine betaine, this DMSP accumulation appears to be an evolutionary novelty. The final step in the syn- thesis of glycine betaine and DMSP is oxidation of the corresponding aldehyde, betaine aldehyde or 3-di- Quaternary ammonium and tertiary sulfonium com- methylsulfoniopropionaldehyde (DMSPald). Leaves of pounds play important roles as compatible osmolytes amaranth (Amaranthus hypochondriacus L.) accumu- late glycine betaine but do not produce detectable or osmoprotectants in the response of flowering plants amounts of DMSP. These leaves contain a betaine-alde- to osmotic stress (for a recent review, see 1). Of these hyde dehydrogenase (BADH) that catalyzes the final compounds, glycine betaine is the most widely distrib- step in glycine betaine synthesis. Here we report that uted, occurring in many species from diverse plant fam- this enzyme efficiently catalyzes the oxidation of ilies; these include Amaranthaceae, Chenopodiaceae, DMSPald. On the basis of V max /K m values, DMSPald is Compositae, Convolvulaceae, Gramineae, Legumino- a better substrate for amaranth BADH than betaine sae, Plumbaginaceae, and Solanaceae (1 – 3). The wide- aldehyde itself. The kinetic mechanism followed by spread occurrence of glycine betaine accumulation im- amaranth BADH at low concentrations of DMSPald is plies that it appeared early in the evolution of flowering similar to that with betaine aldehyde; as determined plants (1). Recent studies of the enzymes and genes of from initial velocity, product, dead-end, and substrate betaine aldehyde synthesis have provided strong sup- inhibition studies, it is a steady-state bi bi with or- port for this inference (4, 5). dered addition of substrates and random release of In certain genera of the families Gramineae and products. Like betaine aldehyde, DMSPald is inhibi- Compositae, glycine betaine occurs together with its tory at high concentrations, at which a slower alter- sulfur analog 3-dimethylsulfoniopropionate (DMSP). 4 nate route of substrate addition takes place. Our re- The genera Spartina and Saccharum (Gramineae) and sults indicate that the evolution of DMSP biosynthesis Wollastonia (Compositae) are the best known examples in flowering plants could have been facile in that it of this (1, 6, 7). Because the Compositae are only dis- required no new aldehyde dehydrogenase; BADH may tantly related to the Gramineae, and because the gen- era Spartina and Saccharum belong to different sub- families within the Gramineae (8), it is probable that 1 This work was supported by grants to R.A.M.-C. from Consejo Nacional de Ciencia y Tecnologı B a (CONACYT-1713-N9209) and to A.D.H. from the National Science Foundation (IBN-9514336). 4 Abbreviations used: BADH, betaine-aldehyde dehydrogenase; 2,3 To whom correspondence should be addressed. Fax: (352) 392 6479 (A.D.H.), (525) 622 5329 (R.A.M.-C.). E-mail: adha@gnv.ifa- DMSPald, 3-dimethylsulfoniopropionaldehyde; DMSP, 3-dimethyl- sulfoniopropionate; EDTA, ethylenediaminetetraacetic acid. s.ufl.edu, clares@servidor.unam.mx. 81 0003-9861/97 $25.00 Copyright  1997 by Academic Press, Inc. All rights of reproduction in any form reserved.