Linked Life Data

14593480

Source:http://linkedlifedata.com/resource/pubmed/id/14593480

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2004-1-8
pubmed:abstractText
Transitory starch is stored during the day inside chloroplasts and then broken down at night for export. Recent data indicate that maltose is the major form of carbon exported from the chloroplast at night but its fate in the cytosol is unknown. An amylomaltase gene ( malQ) cloned from Escherichia coli is necessary for maltose metabolism in E. coli. We investigated whether there is an amylomaltase in the cytosol of plant leaves and the role of this enzyme in plants. Two mutants of Arabidopsis thaliana (L) Heynh. were identified in which the gene encoding a putative amylomaltase enzyme [ disproportionating enzyme 2, DPE2 (DPE1 refers to the plastid version of this enzyme)] was disrupted by a T-DNA insertion. Both dpe2-1 and dpe2-2 plants exhibited a dwarf phenotype and accumulated a large amount of maltose. In addition, dpe2 mutants accumulated starch and a water-soluble, ethanol/KCl-insoluble maltodextrin in their chloroplasts. At night, the amount of sucrose in dpe2 plants was lower than that in wild-type plants. These results show that Arabidopsis has an amylomaltase that is involved in the conversion of maltose to sucrose in the cytosol. We hypothesize that knocking out amylomaltase blocks the conversion from maltose to sucrose, and that the higher amount of maltose feeds back to limit starch degradation reactions in chloroplasts. As a result, dpe2 plants have higher maltose, higher starch, and higher maltodextrin but lower nighttime sucrose than wild-type plants. Finally, we propose that maltose metabolism in the cytosol of Arabidopsis leaves is similar to that in the cytoplasm of E. coli.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0032-0935
pubmed:author
pubmed:issnType
Print
pubmed:volume
218
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
466-73
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
The role of amylomaltase in maltose metabolism in the cytosol of photosynthetic cells.
pubmed:affiliation
Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI 53706, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.