View source for 1ql1

[[Image:1ql1.gif|left|200px]]

 {{Structure
|PDB= 1ql1 |SIZE=350|CAPTION= <scene name='initialview01'>1ql1</scene>, resolution 3.1&Aring;
|SITE= 
|LIGAND= 
|ACTIVITY= 
|GENE= 
}}

'''INOVIRUS (FILAMENTOUS BACTERIOPHAGE) STRAIN PF1 MAJOR COAT PROTEIN ASSEMBLY'''


==Overview==
The major coat protein in the capsid of Pf1 filamentous bacteriophage (Inovirus) forms a helical assembly of about 7000 identical protein subunits, each of which contains 46 amino-acid residues and can be closely approximated by a single gently curved alpha-helix. Since the viral DNA occupies the core of the tubular capsid and appears to make no significant specific interactions with the capsid proteins, the capsid is a simple model system for the study of the static and dynamic properties of alpha-helix assembly. The capsid undergoes a reversible temperature-induced structural transition at about 283 K between two slightly different helix forms. The two forms can coexist without an intermediate state, consistent with a first-order structural phase transition. The molecular model of the higher temperature form was refined using improved X-ray fibre diffraction data and new refinement and validation methods. The refinement indicates that the two forms are related by a change in the orientation of the capsid subunits within the virion, without a significant change in local conformation of the subunits. On the higher temperature diffraction pattern there is a region of observed intensity that is not consistent with a simple helix of identical subunits; it is proposed that the structure involves groups of three subunits which each have a slightly different orientation within the group. The grouping of subunits suggests that a change in subunit libration frequency could be the basis of the Pf1 structural transition; calculations from the model are used to explore this idea.

==About this Structure==
1QL1 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_phage_pf1 Pseudomonas phage pf1]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QL1 OCA]. 

==Reference==
The molecular structure and structural transition of the alpha-helical capsid in filamentous bacteriophage Pf1., Welsh LC, Symmons MF, Marvin DA, Acta Crystallogr D Biol Crystallogr. 2000 Feb;56(Pt 2):137-50. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/10666593 10666593]
[[Category: Pseudomonas phage pf1]]
[[Category: Single protein]]
[[Category: Marvin, D A.]]
[[Category: Symmons, M F.]]
[[Category: Welsh, L C.]]
[[Category: helical virus]]
[[Category: helical virus coat protein]]
[[Category: inovirus]]
[[Category: ssdna viruse]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 13:39:04 2008''