2024-03-28T13:15:44Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/978232021-11-22T12:49:52Zcom_10261_118com_10261_6col_10261_371
No evidence for the occurrence of substrate inhibition of Arabidopsis thaliana sucrose synthase-1 (AtSUS1) by fructose and UDP-glucose
Almagro, Goizeder
Baroja-Fernández, Edurne
Muñoz Pérez, Francisco José
Bahaji, Abdellatif
Etxebarría, E.
Li, Jun
Montero, Manuel
Hidalgo, Maite
Sesma, María Teresa
Pozueta Romero, Javier
Sucrose synthase (SuSy) catalyzes the reversible conversion of sucrose and NDP into the corresponding nucleotidesugars and fructose. The Arabidopsis genome possesses six SUS genes (AtSUS1-6) that code for proteins with SuSy activity. As a first step to investigate optimum fructose and UDP-glucose (UDPG) concentrations necessary to measure maximum sucrose-producing SuSy activity in crude extracts of Arabidopsis, in this work we performed kinetic analyses of recombinant AtSUS1 in two steps: (1) SuSy reaction at pH 7.5, and (2) chromatographic measurement of sucrose produced in step 1. These analyses revealed a typical Michaelis-Menten behavior with respect to both UDPG and fructose, with Km values of 50 μM and 25 μM, respectively. Unlike earlier studies showing the occurrence of substrate inhibition of UDP-producing AtSUS1 by fructose and UDP-glucose, these analyses also revealed no substrate inhibition of AtSUS1 at any UDPG and fructose concentration. By including 200 μM fructose and 1 μM UDPG in the SuSy reaction assay mixture, we found that sucrose-producing SuSy activity in leaves and stems of Arabidopsis were exceedingly higher than previously reported activities. Furthermore, we found that SuSy activities in organs of the sus1/sus2/sus3/sus4 mutant were ca. 80-90% of those found in WT plants. © 2012 Landes Bioscience.
This research was partially supported by the grant BIO2010-18239 from the Comisión Interministerial de Ciencia y Tecnología and Fondo Europeo de Desarrollo Regional (Spain) and by Iden Biotechnology S.L. G.A. acknowledges a fellowship from the Public University of Navarra.
Peer Reviewed
2014-06-05T11:26:09Z
2014-06-05T11:26:09Z
2012
2014-06-05T11:26:09Z
artículo
http://purl.org/coar/resource_type/c_6501
doi: 10.4161/psb.20601
issn: 1559-2316
Plant Signaling and Behavior 7(7): 799-802 (2012)
http://hdl.handle.net/10261/97823
10.4161/psb.20601
22751299
none
Landes Bioscience