Crystal Structure of the Carboxy-Terminal Region of the Bacteriophage T4 Proximal Long Tail Fiber Protein Gp34.

Long tail fibers of bacteriophage T4 are formed by proteins gp34, gp35, gp36, and gp37, with gp34 located at the phage-proximal end and gp37 at the phage-distal, receptor-binding end. We have solved the structure of the carboxy-terminal region of gp34, consisting of amino acids 894-1289, by single-wavelength anomalous diffraction and extended the structure to amino acids 744-1289 using data collected from crystals containing longer gp34-fragments. The structure reveals three repeats of a mixed α-ß fibrous domain in residues 744 to 877. A triple-helical neck connects to an extended triple ß-helix domain (amino acids 900-1127) punctuated by two ß-prism domains. Next, a ß-prism domain decorated with short helices and extended ß-helices is present (residues 1146-1238), while the C-terminal end is capped with another short ß-helical region and three ß-hairpins. The structure provides insight into the stability of the fibrous gp34 protein.

Crystallization of the carboxy-terminal region of the bacteriophage T4 proximal long tail fibre protein gp34.

The phage-proximal part of the long tail fibres of bacteriophage T4 consists of a trimer of the 1289 amino-acid gene product 34 (gp34). Different carboxy-terminal parts of gp34 have been produced and crystallized. Crystals of gp34(726-1289) diffracting X-rays to 2.9 Šresolution, crystals of gp34(781-1289) diffracting to 1.9 Šresolution and crystals of gp34(894-1289) diffracting to 3.0 and 2.0 Šresolution and belonging to different crystal forms were obtained. Native data were collected for gp34(726-1289) and gp34(894-1289), while single-wavelength anomalous diffraction data were collected for selenomethionine-containing gp34(781-1289) and gp34(894-1289). For the latter, high-quality anomalous signal was obtained.