Linked Life Data

21659511

Source:http://linkedlifedata.com/resource/pubmed/id/21659511

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
31
pubmed:dateCreated
2011-8-1
pubmed:abstractText
Aminopeptidases catalyze N-terminal peptide bond hydrolysis and occupy many diverse roles across all domains of life. Here we present evidence that an M1-family aminopeptidase, PfA-M1, has been recruited to specialized roles in the human malaria parasite Plasmodium falciparum. PfA-M1 is abundant in two subcellular compartments in asexual intraerythrocytic parasites; that is, the food vacuole, where the catabolism of host hemoglobin takes place, and the nucleus. A unique N-terminal extension contributes to the observed dual targeting by providing a signal peptide and putative alternate translation initiation sites. PfA-M1 exists as two major isoforms, a nuclear 120-kDa species and a processed species consisting of a complex of 68- and 35-kDa fragments. PfA-M1 is both stable and active at the acidic pH of the food vacuole lumen. Determination of steady-state kinetic parameters for both aminoacyl-?-naphthylamide and unmodified dipeptide substrates over the pH range 5.0-8.5 reveals that k(cat) is relatively insensitive to pH, whereas K(m) increases at pH values below 6.5. At the pH of the food vacuole lumen (5.0-5.5), the catalytic efficiency of PfA-M1 remains high. Consistent with the kinetic data, the affinity of peptidic competitive inhibitors is diminished at acidic pH. Together, these results support a catalytic role for PfA-M1 in the food vacuole and indicate the importance of evaluating the potency of peptidic inhibitors at physiologically relevant pH values. They also suggest a second, distinct function for this enzyme in the parasite nucleus.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
1083-351X
pubmed:author
pubmed:issnType
Electronic
pubmed:day
5
pubmed:volume
286
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
27255-65
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
Distribution and biochemical properties of an M1-family aminopeptidase in Plasmodium falciparum indicate a role in vacuolar hemoglobin catabolism.
pubmed:affiliation
Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
pubmed:publicationType
Journal Article, Research Support, N.I.H., Extramural