Descrição
In view of the abundacy of phages (1), even rare phage-induced events are frequent at the
global level. They have a staggering ecological impact on the bacterial population and in
the evolution of bacterial genomic structure upon virus-host interactions, acting as agents
in the recycling of organic matter and presenting a valuable tool in molecular biology and
epidemiology. Th focus on genomic research have revealed information on open reading
frames of proteins of interest (2). Increasing interest has been given to phage (endo )lysins
in molecular biology, biotechnology and medicine. Lysins are phage lytic enzymes that
break down the peptidoglycan of the bacterial cell wall at the terminal stage of the phage
reproduction cycle, to release the phage progeny with the consequent death of the
bacterial cells (3). Despite the increasing number of genomes in Genbank:, no effort has
been made so far to understand the relation between lysins and their phage family and
host species, presenting challenges in their annotation, comparative analysis, and
representation. The almost 700 complete phage genomes deposited in the NCBI database
were searched for the presence of lysins by making use of the pfam ( 4) identified
domains and BLAST comparison of putative/unidentified complete genome against
known lysins. In approximately 5% of the phage genomes it was not possible to identify
any lysin. The identified enzymes were used to construct a phylogenetic tree with Phylip
(5), using Neighbor-Joining, Maximum Likelihood and Parsimony algorithms (6). From
the resulting tree, we were able to present a phage-lysin characterization network analysis
taking into account the lysin aa sequence and the different phage classes (Family/Genus)
and host species to study their evolutionary stories. Regarding the phage families,
muramidases, amidases and peptidases are the largest type of lysins in Myoviridae,
Podoviridae and Siphoviridae phages respectively. Grouped data will also be used to
identify conserved domains among lysins of different phages which will play an
important role in the annotation of the unidentified lytic cassette of sequenced phages.
; Melo, Luís D. R. 
