Microbiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Microbiology 154 (2008), 1656-1667; DOI  10.1099/mic.0.2008/017103-0
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Quezada, H.
Right arrow Articles by González, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Quezada, H.
Right arrow Articles by González, A.
Agricola
Right arrow Articles by Quezada, H.
Right arrow Articles by González, A.
Microbiology 154 (2008), 1656-1667; DOI  10.1099/mic.0.2008/017103-0
© 2008 Society for General Microbiology

Specialization of the paralogue LYS21 determines lysine biosynthesis under respiratory metabolism in Saccharomyces cerevisiae

Héctor Quezada1, Cristina Aranda1, Alexander DeLuna1, Hugo Hernández1, Mario L. Calcagno2, Álvaro Marín-Hernández3 and Alicia González1

1 Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, México DF 04510, México
2 Laboratorio de Fisicoquímica e Ingeniería de Proteínas, Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, México DF 04510, México
3 Instituto Nacional de Cardiología, Departamento de Bioquímica, Tlalpan, México DF, México

Correspondence
Alicia González
amanjarr{at}ifc.unam.mx

In the yeast Saccharomyces cerevisiae, the first committed step of the lysine biosynthetic pathway is catalysed by two homocitrate synthases encoded by LYS20 and LYS21. We undertook a study of the duplicate homocitrate synthases to analyse whether their retention and presumable specialization have affected the efficiency of lysine biosynthesis in yeast. Our results show that during growth on ethanol, homocitrate is mainly synthesized through Lys21p, while under fermentative metabolism, Lys20p and Lys21p play redundant roles. Furthermore, results presented in this paper indicate that, in contrast to that which had been found for Lys20p, lysine is a strong allosteric inhibitor of Lys21p (Ki 0.053 mM), which, in addition, induces positive co-operativity for {alpha}-ketoglutarate ({alpha}-KG) binding. Differential lysine inhibition and modulation by {alpha}-KG of the two isozymes, and the regulation of the intracellular amount of the two isoforms, give rise to an exquisite regulatory system, which balances the rate at which {alpha}-KG is diverted to lysine biosynthesis or to other metabolic pathways. It can thus be concluded that retention and further biochemical specialization of the LYS20- and LYS21-encoded enzymes with partially overlapping roles contributed to the acquisition of facultative metabolism.

Abbreviations: AAA, {alpha}-amino adipate; {alpha}-AASA, 2-aminoadipate semialdehyde; AcCoA, acetyl CoA; DCIP, 2,6-dichloroindophenol; {alpha}-KG, {alpha}-ketoglutarate






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
INT J SYST EVOL MICROBIOL MICROBIOLOGY J GEN VIROL
J MED MICROBIOL ALL SGM JOURNALS
Copyright © 2008 Society for General Microbiology.