Linked Life Data

9398263

Source:http://linkedlifedata.com/resource/pubmed/id/9398263

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
49
pubmed:dateCreated
1998-1-6
pubmed:abstractText
The Synechococcus PCC7942 metallothionein repressor gene smtB has been cloned into a high expression vector and the protein purified to near homogeneity (>/=98%). Analytical ultracentrifugation studies demonstrate that the protein is predominantly dimeric in 0.1 M NaCl, pH 7.4, and 22 degrees C, exhibiting a monomer-dimer-tetramer equilibrium. The monomer-dimer (Ka(1,2)) and the dimer-tetramer (Ka(2,4)) association constants are 3.24 x 10(5) and 9.90 x 10(2) M-1, respectively. The repressor binds two Zn2+ ions per subunit with an overall Kd of 3.49 x 10(-6) M. In the presence of Zn2+, Ka(1, 2) increases by 2 orders of magnitude to 1.25 x 10(7) M-1 and the apparent weight-averaged sedimentation coefficient increases from 2. 00 to 2.22 S. The fact that the increase in sedimentation coefficient is greater than that predicted by increased dimerization is interpreted as caused by compaction of the structure in the presence of metal ions. At pH 6.0, 0.1 M NaCl, and 22 degrees C, the protein exhibits only a monomer-dimer equilibrium, with Ka(1,2) = 1.52 x 10(7) M-1 which is almost identical to that seen upon binding Zn2+ at pH 7.4. The compaction and conformational change in SmtB caused by Zn2+ is consistent with a role for this altered quaternary state in derepression of smtA in Synechococcus challenged with heavy metal ions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
9
pubmed:volume
36
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
15343-8
pubmed:dateRevised
2009-7-17
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
The cyanobacterial repressor SmtB is predominantly a dimer and binds two Zn2+ ions per subunit.
pubmed:affiliation
The Graduate Program in Biophysical Sciences, Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294-2041, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't