INVESTIGADORES
IGLESIAS Alberto Alvaro
congresos y reuniones científicas
Título:
In Vivo Analysis of Glycogen Biosynthetic Pathway in Anabaena sp. and E. coli
Autor/es:
S.P. RIUS, A.A. IGLESIAS, D.F. GOMEZ-CASATI
Lugar:
Bariloche, Río Negro, Argentina
Reunión:
Congreso; XXXIX Reunión Anual de SAIB; 2003
Institución organizadora:
SAIB
Resumen:
PL-P25.IN VIVO ANALYSIS OF GLYCOGEN BIOSYNTHETICPATHWAY IN ANABAENA sp. AND E. COLIRius SP1, Iglesias AA2, and Gómez-Casati DF.11Instituto de Investigaciones Biotecnológicas-Instituto Tecnológicode Chascomús (IIB-INTECH). 2Bioquímica Básica deMacromoléculas, Grupo de Enzimología Molecular, Fac. Bioq.Cs. Biológicas, Univ. Nac. del Litoral. E-mail:srius@intech.gov.arCyanobacterial and E. coli cells were permeabilized using amixture of toluene:ethanol or toluene, respectively.Permeabilization was confirmed after addition of fluoresceindiacetate and microscopic visualization. After the incubation ofthe treated cells with ADPGlc PPase substrates, ATP and[14C]Glc1P; or glycogen synthase substrate, [14C]ADPGlc,labelled alpha-1,4-glucan was recovered. Addition of external nonradioactive ADPGlc in the incubation media with ATP and[14C]Glc1P did not affect the [14C]Glc incorporation into theglucan. Moreover, there was only 40% of the total incorporationof [14C]ADPGlc when the cells were in the presence of ADPGlcPPase non-labelled substrates. Structural data from Blue nativePAGE, western blot analysis and co-immunoprecipitation, suggestthe existence of protein-protein interactions between the enzymesinvolved in glycogen biosynthesis in Anabaena and E. coli. Resultssuggest a direct transfer of ADPGlc between ADPGlc PPase andglycogen synthase (metabolite channeling). This is a process bywhich a metabolite is directly transferred from one enzyme activesite to the next without being released free into solution. The directchanneling of an intermediate between enzymes catalyzingconsecutive reactions in a biochemical pathway offers thepossibility of an efficient and exclusive metabolite delivery. Thismechanism may allow to maintain a high flux of substrates in theglycogen biosynthetic pathway under different physiologicalconditions.