STRUCTURE-BASED PHYLOGENY OF METALLO-BETA-

LACTAMASES

A.Nilavazhagan

(Reg.No:08MTBI09)

PAPER..

ΒETA LACTAMASES..

Lactam antibiotics are the most widely used antibiotics.

The major cause of resistance to -lactam antibiotics is the presence of –lactamases.

These enzymes inactivate –lactam antibiotics by hydrolyzing the -lactam bond in those drugs.

ON THE PAPER.. The metallo--lactamases fall into two groups: Ambler class B

subgroups B1 and B2 and Ambler class B subgroup B3. The two groups are so distantly related that there is no detectable sequence homology between members of the two different groups, but homology is clearly detectable at the protein structure level. The multiple structure alignment program MAPS has been used to align the structures of eight metallo--lactamases and five structurally homologous proteins from the metallo--lactamase superfamily, and that alignment has been used to construct a phylogenetic tree of the metallo--lactamases. The presence of genes from Eubacteria,

Archaebacteria, and Eukaryota on that tree is consistent with a

very ancient origin of the metallo--lactamase family.

PURPOSE OF THIS STUDY..

To elucidate the relationship on the basis of a structure-

based phylogeny.

APPROACHES AND RESOURCES.. MAPS

Multiple Alignment of Protein Structures. VAST & DALI

For identifying structural neighbors. PAUP

Estimation of phylogenetic trees. Jackknife

UPSHOT..

Structure-based multiple alignment of homologous amino acids

UPSHOT.. Neighbor-joining tree based on structural multiple alignment

UPSHOT.. Jackknife neighbor-joining tree

INFERENCE.. The structure-based phylogeny shows that the

metallo-beta-lactamases and the beta-lactamase-like domain of rubridoxin oxidoreductase descended from a common ancestor at node A.

It was estimated that the subgroup B1B2 proteins arose shortly after the proteobacteria diverged from the gram-positive bacteria, about 2.2 billion years ago, and that the true metallo--lactamases of subgroup B3 arose earlier than 2.2billion years ago

WHAT I HAVE DONE.. Eight Metallo-Beta-Lactamases from different

oragnisms and five structurally similar groups obtained.

Multiple sequence alignment was performed to determine the similarity between the obtained sequences.

Phylogenetic analysis was performed for the aligned sequences.

APPROACHES AND RESOURCES.. The program Clustal Omega

(http://www.ebi.ac.uk/Tools/msa/clustalo/) was used to perform multiple sequence alignment.

Phylogenetic analysis was performed for the aligned sequences using MEGA (Molecular Evolutionary Genetic Analysis) version 5.1. Phylogenetic tree was constructed in MEGA using

Neighbour-joining method. Bootstrap method will validate the given model by

random sampling.

UPSHOT..

Structure based Multiple alignment of homologous aminoacids using clustal omega

UPSHOT..

Neighbor-joining tree based on Multiple alignment

UPSHOT..

Bootstrap neighbor-joining tree based on 500 replicates

CONCLUSION.. It was estimated that the

subgroup B1_B2 proteins arose shortly after the proteobacteria diverged from the gram-positive bacteria, about 2.2 billion years ago, and that the true metallo-β lactamases of subgroup B3 arose earlier than 2.2 billion years ago.

MEGA

PAUP

NANDRI..