Generation of diploid Pichia pastoris strains by mating and their application for recombinant protein production.

Background: Yeast mating provides an efficient means for strain and library construction. However, biotechnological applications of mating in the methylotrophic yeast Pichia pastoris have been hampered because of concerns about strain stability of P. pastoris diploids.

Crystallogenesis of bacteriophage P22 tail accessory factor gp26 at acidic and neutral pH.

Gp26 is one of three phage P22-encoded tail accessory factors essential for stabilization of viral DNA within the mature capsid. In solution, gp26 exists as an extended triple-stranded coiled-coil protein which shares profound structural similarities with class I viral membrane-fusion protein. In the cryo-EM reconstruction of P22 tail extracted from mature virions, gp26 forms an approximately 220 angstroms extended needle structure emanating from the neck of the tail, which is likely to be brought into contact with the cell's outer membrane when the viral DNA-injection process is initiated.

Bacteriophage P22 tail accessory factor GP26 is a long triple-stranded coiled-coil.

P22 is a well characterized tailed bacteriophage that infects Salmonella enterica serovar Typhimurium. It is characterized by a "short" tail, which is formed by five proteins: the dodecameric portal protein (gp1), three tail accessory factors (gp4, gp10, gp26), and six trimeric copies of the tail-spike protein (gp9). We have isolated the gene encoding tail accessory factor gp26, which is responsible for stabilization of viral DNA within the mature phage, and using a variety of biochemical and biophysical techniques we show that gp26 is very likely a triple stranded coiled-coil protein.