201l
From Proteopedia
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HOW AMINO-ACID INSERTIONS ARE ALLOWED IN AN ALPHA-HELIX OF T4 LYSOZYME
Overview
Studies of extant protein sequences indicate that amino-acid insertions and deletions are preferentially located in loop regions, which has traditionally been explained as the result of selection removing deleterious mutations within secondary structural elements from the population. But there is no a priori reason to discount the possibility that insertions within secondary structure could either be tolerated until compensatory mutations arise, or have effects that are propagated away from secondary structure into loops. Earlier studies have indicated that insertions are generally tolerated, although much less well within secondary structure elements than in loop regions. Here we show that amino-acid insertions in an alpha-helix of T4 lysozyme can be accepted in two different ways. In some cases the inserted amino acids are accommodated within the helix, leading to the translocation of wild-type residues from the helix to the preceding loop. In other cases the insertion causes a 'looping-out' in the first or last turn of the helix. The individual structural responses seem to be dominated by the maintenance of the interface between the helix and the rest of the protein.
About this Structure
201L is a Single protein structure of sequence from Enterobacteria phage t2 with as ligand. Active as Lysozyme, with EC number 3.2.1.17 Full crystallographic information is available from OCA.
Reference
How amino-acid insertions are allowed in an alpha-helix of T4 lysozyme., Heinz DW, Baase WA, Dahlquist FW, Matthews BW, Nature. 1993 Feb 11;361(6412):561-4. PMID:8429913
Page seeded by OCA on Thu Feb 21 16:20:50 2008
