Linked Life Data

11234964

Source:http://linkedlifedata.com/resource/pubmed/id/11234964

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2001-3-7
pubmed:abstractText
The filamentous hemiascomycete Ashbya gossypii is used for industrial riboflavin production. We examined riboflavin uptake and excretion at the plasma membrane using riboflavin auxotrophic and overproducing mutants. The riboflavin uptake system had low activity [Vmax = 20 +/- 4 nmol min(-1) g(-1) mycelial dry weight (dw)] and high affinity (KM = 40 +/- 12 microM). Inhibitor studies with the analogs FMN and FAD revealed high specificity of the uptake system. Excretion of riboflavin was not the consequence of non-specific permeability of the plasma membrane. Excretion rates in the mid-production phase were determined to be 2.5 nmol min(-1) g(-1) dw for wild-type cells and 66.7 nmol min(-1) g(-1) dw for an overproducing mutant, respectively. Inhibition of the reverse reaction, riboflavin uptake, led to an increase in apparent riboflavin efflux in the early production phase, indicating the presence of a separate excretion carrier. Riboflavin accumulation in A. gossypii vacuoles leading to product retention was found to be a secondary transport process. To address the question of whether a flux from the vacuoles back into the cytoplasm is present, we characterized efflux in hyphae in which the plasma membrane was permeabilized with digitonin. Efflux kinetics across the vacuolar membrane were unaffected by the lack of vacuolar H+ATPase activity and ATP, suggesting a passive mechanism. Based on the characterization of riboflavin transport processes in this study, the design of new production strains with improved riboflavin excretion may be possible.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0175-7598
pubmed:author
pubmed:issnType
Print
pubmed:volume
55
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
85-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Carrier-mediated transport of riboflavin in Ashbya gossypii.
pubmed:affiliation
Institut für Biochemie, Universität zu Köln, Cologne, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't