发信人: doggiebear (doggiebear), 信区: Biology
标 题: Re: Second Paper - Random Journal Club
发信站: Unknown Space - 未名空间 (Sat Oct 25 16:06:16 2003) WWW-POST





Mycobacteriaphage (EM) image




alpha3 bacteriaphage (structure determined by X-ray and cryo-EM)


Look at the figure above, the tail of the phage is kind of fibular protein,
not globular as most proteins do.

If you look at the genome of bacteriaphage, you will find most recombination
events are outside the gene boundary. The explaination is that any
recombination within a gene will result in defective protein. This obviously
will lead to the elimination of the phages that carries this recomination
event.

However, rampant in-the-gene recombination events can be observed within the
genome region coding the tail protein. Why? The explaination is because the
tail protein is a fibular protein, therefore, the amino acids in distant part
of the sequence will not be brough together to interact with each other. So as
far as the resulting protein still forms a fibular structure, the recombinant
event will only have local effect and the progeny will not have much defect.

The evolution result of this intragenic tail protein mosaicity is to produce
many phages with different host specificity, which increases the diversity of
the bacteriaphages. And the phage tail proteins may also represent the
first-look of the recombinant products while proteins elsewhere are the
modified version after natural selection kicks in.




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