Overveiw Metallo β Lactamases enzymes that inactivate β lactam antibiotics by catalyzing the hydrolysis of the four membered ring no clinically available inhibitors General Structure ID: 927641
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Slide1
Metallo-β-Lactamase
Ian Desmond
Slide2Overveiw
Metallo
-β-
Lactamases- enzymes that inactivate β-lactam antibiotics, by catalyzing the hydrolysis of the four-membered ringno clinically available inhibitors
Slide3General Structure
Three classes of
Metallo
-β-Lactamases based on their amino acid sequences: B1, B2, B3All classes possess: 1) one or two potential Zinc ion binding sites in the active site
2) similar
αβ
/
βα
fold
Slide4Class B1
Broad Spectrum
Active with one or two Zn ions in active site
Zn 1 site: 3 HistidineZn 2 site: Asparagine-Cysteine-HistidineEffect of Zn binding:
Binding of 2 Zn
atoms for
optimal
hydrolysis
Examples:Bc
II, IMP- I,
Ccr
A, VIM
, GIM, SPM-1
Slide5Class B2
High
specificity for hydrolyzing
carbapenemsAeromonas enzymesZn 1 site: 2 Histidine, 1 Asparagine
Zn 2 site:
Asparagine-Cysteine-Histidine
Effect of Zn binding:
Binding of
second Zn
atom is
inhibitory
Catalytic Zn cofactor occupies the Zn 2 site
Examples:
Cph
A, Sfh-1
Slide6Class B3
High
specifi
city for hydrolyzing cephalosporinsHas a Tetrameric enzyme form (LI), all other forms are monomeric
Zn 1 site:
3
Histidine
Zn 2 site:
Asparagine-Histidine-Histidine
Effect of Zn binding:
Binding of 2 Zn
atoms for
optimal
hydrolysis
Examples:
LI, FEZ-1,
Gob-1, CAU-1
Slide7Primary Structure
their primary structures exhibit low degrees of sequence
isologygenerally less than 43%
Slide8Secondary Structure
two domains of roughly equivalent topology
αβ
/βα foldN-terminal domain=β1β2β
3
β
4
β
5
α
1
β
6
α
2
β
7
α
3 C-terminal domain=
β
8
β
9
β
10
β
11
α
4
β
12
α
5
Slide9Secondary Structure
Slide10Protein Fold
Slide11Tertiary Structure
Their three-dimensional
structures show high degrees of similarityeach domain contains ββββαβα motif. No significant sequence homology was found between the two motifs.
Slide12Quaternary Structure
Zn-1 is coordinated to three
histidines
and a water molecule. Zn-2 interacts with a cysteine, an aspartic acid, and a
histidine
(
BcII
,
IMP-1, and
CcrA
) or an aspartic acid and two
histidines
(for L1)
and two water molecules in a
trigonal
pyramid.
di
-zinc
form=one water molecule is bridged between the metal
ions.
Slide13Slide14Active Site
Slide15Structure of Active Site
active site is located at the bottom of a groove running between the two
β
sheetsThe four Zn2+ ligands are arranged in a distorted tetrahedral shape.Seven out of the nine
strictly conserved
residues are located in the active site:
His88, Asp9O
, Leull4, Hisl49, Glyl79, Asnl80 and His210.
Slide16Works Cited
Images
http://www.rcsb.org/pdb/explore/explore.do?structureId=2WRS
http://jb.oxfordjournals.org/content/140/4/535.fullWeb Siteshttp://aac.asm.org/cgi/content/full/45/4/1254
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC90352/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1168685/
http://cmbi.bjmu.edu.cn/news/report/2010/pdf/ndm_7.pdf
https://webmail.stedwards.edu/service/home/~/article1.pdf?auth=co&loc=en_US&id=46820&part=2
https://webmail.stedwards.edu/service/home/~/article2.pdf?auth=co&loc=en_US&id=46820&part=3
https://webmail.stedwards.edu/service/home/~/emboj00044-0024.pdf?auth=co&loc=en_US&id=46820&part=5
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC394593/pdf/emboj00044-0024.pdf