Plant Physiol. Illumina
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
QUICK SEARCH:   [advanced]


     

Plant Physiology Preview
Published on January 19, 2007; 10.1104/pp.106.091736

OPEN ACCESS ARTICLE
This Article
Free via Open Access: OA
Right arrow Full Text (Plant Physiology Preview (PDF))
Right arrowOA All Versions of this Article:
143/3/1385    most recent
pp.106.091736v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
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 Web of Science (6)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Cumino, A. C.
Right arrow Articles by Salerno, G. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Cumino, A. C.
Right arrow Articles by Salerno, G. L.
Agricola
Right arrow Articles by Cumino, A. C.
Right arrow Articles by Salerno, G. L.

Received October 21, 2006
Accepted January 8, 2007

Carbon Cycling in Anabaena sp. PCC 7120. Sucrose Synthesis in the Heterocysts and Possible Role in Nitrogen Fixation

Andrea C. Cumino , Clarisa Marcozzi , Roberto Barreiro , and Graciela L. Salerno *

Centro de Investigaciones Biológicas (CIB), Fundación para Investigaciones Biológicas Aplicadas (FIBA), Vieytes 3103, C.C. 1348, 7600 Mar del Plata, Argentina

* Corresponding author; email: gsalerno{at}fiba.org.ar.

Nitrogen available to plants mostly originates from N2 fixation carried out by prokaryotes. Certain cyanobacterial species contribute to this energetically expensive process related to carbon metabolism. Several filamentous strains differentiate heterocysts, specialized N2-fixing cells. To understand how carbon and nitrogen metabolism are regulated in photo-diazotrophically grown organisms, we investigated the role of sucrose biosynthesis in N2 fixation in Anabaena sp. PCC 7120 (also known as Nostoc sp. PCC 7120). The presence of two sucrose-phosphate synthases, SPS-A and SPS-B, directly involved in Suc synthesis with different glucosyl donor specificity seems to be important in the N2-fixing filament. Measurement of enzyme activity and polypeptide levels plus RT-PCR experiments showed that total SPS expression is greater in cells grown in N2 versus combined-N conditions. Only SPS-B, however, was seen to be active in the heterocyst, as confirmed by analysis of gfp-reporters. SPS-B gene expression is likely controlled at the transcriptional initiation level, probably in relation to a global N regulator. Metabolic control analysis indicated that the metabolism of glycogen and sucrose are likely interconnected in N2-fixing filaments. These findings suggest that N2 fixation may be spatially compatible with sucrose synthesis and support the role of the disaccharide as an intermediate in the reduced carbon flux in heterocyst-forming cyanobacteria.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
ASPB Publications PLANT PHYSIOLOGY® THE PLANT CELL
Copyright © 2007 by the American Society of Plant Biologists