Linked Life Data

20853856

Source:http://linkedlifedata.com/resource/pubmed/id/20853856

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
40
pubmed:dateCreated
2010-12-14
pubmed:databankReference
pubmed:abstractText
Nicotinamidases are salvage enzymes that convert nicotinamide to nicotinic acid. These enzymes are essential for the recycling of nicotinamide into NAD(+) in most prokaryotes and most single-cell and multicellular eukaryotes, but not in mammals. The significance of these enzymes for nicotinamide salvage and for NAD(+) homeostasis has stimulated interest in nicotinamidases as possible antibiotic targets. Nicotinamidases are also regulators of intracellular nicotinamide concentrations, thereby regulating signaling of downstream NAD(+)-consuming enzymes, such as the NAD(+)-dependent deacetylases (sirtuins). Here, we report several high-resolution crystal structures of the nicotinamidase from Streptococcus pneumoniae (SpNic) in unliganded and ligand-bound forms. The structure of the C136S mutant in complex with nicotinamide provides details about substrate binding, while a trapped nicotinoyl thioester in a complex with SpNic reveals the structure of the proposed thioester reaction intermediate. Examination of the active site of SpNic reveals several important features, including a metal ion that coordinates the substrate and the catalytically relevant water molecule and an oxyanion hole that both orients the substrate and offsets the negative charge that builds up during catalysis. Structures of this enzyme with bound nicotinaldehyde inhibitors elucidate the mechanism of inhibition and provide further details about the catalytic mechanism. In addition, we provide a biochemical analysis of the identity and role of the metal ion that orients the ligand in the active site and activates the water molecule responsible for hydrolysis of the substrate. These data provide structural evidence of several proposed reaction intermediates and allow for a more complete understanding of the catalytic mechanism of this enzyme.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
1520-4995
pubmed:author
pubmed:issnType
Electronic
pubmed:day
12
pubmed:volume
49
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
8803-12
pubmed:dateRevised
2011-10-12
pubmed:meshHeading
pubmed:year
2010
pubmed:articleTitle
High-resolution crystal structures of Streptococcus pneumoniae nicotinamidase with trapped intermediates provide insights into the catalytic mechanism and inhibition by aldehydes .
pubmed:affiliation
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural