PMID:22429790

Citation	Thomas, JA, Weintraub, ST, Wu, W, Winkler, DC, Cheng, N, Steven, AC and Black, LW (2012) Extensive proteolysis of head and inner body proteins by a morphogenetic protease in the giant Pseudomonas aeruginosa phage φKZ. Mol. Microbiol. 84:324-39
Abstract	Encased within the 280 kb genome in the capsid of the giant myovirus φKZ is an unusual cylindrical proteinaceous 'inner body' of highly ordered structure. We present here mass spectrometry, bioinformatic and biochemical studies that reveal novel information about the φKZ head and the complex inner body. The identification of 39 cleavage sites in 19 φKZ head proteins indicates cleavage of many prohead proteins forms a major morphogenetic step in φKZ head maturation. The φKZ head protease, gp175, is newly identified here by a bioinformatics approach, as confirmed by a protein expression assay. Gp175 is distantly related to T4 gp21 and recognizes and cleaves head precursors at related but distinct S/A/G-X-E recognition sites. Within the φKZ head there are six high-copy-number proteins that are probable major components of the inner body. The molecular weights of five of these proteins are reduced 35-65% by cleavages making their mature form similar (26-31 kDa), while their precursors are dissimilar (36-88 kDa). Together the six abundant proteins sum to the estimated mass of the inner body (15-20 MDa). The identification of these proteins is important for future studies on the composition and function of the inner body.
Links	PubMed PMC3323674 Online version:10.1111/j.1365-2958.2012.08025.x
Keywords	Mass Spectrometry; Molecular Weight; Myoviridae/chemistry; Myoviridae/enzymology; Myoviridae/physiology; Peptide Hydrolases/metabolism; Proteolysis; Pseudomonas Phages/chemistry; Pseudomonas Phages/enzymology; Pseudomonas Phages/physiology; Pseudomonas aeruginosa/virology; Viral Proteins/metabolism; Virus Assembly
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BPDPK:Q8SD18		GO:0006508: proteolysis	ECO:0000250:	UniProtKB:D9IEK7	P		From first two paragraphs under the "Identification of φKZ gp175 as the morphogenetic protease" says "we used local implementations of the Sequence Analysis and Modeling System and HHpred.The E-value of this match was only 3, however the HHpred P-value, which takes secondary structure into account, was 2.5E-05. This match was solidified using a custom T4 gp21 HHM powerful enough to detect an HHM based on the U35 peptidase family at E-values of 3.5E-05. Members of the U35 peptidase family contain diverged, but known, homologs to the T4 protease, such as the HK97 protease."	complete CACAO 11661
BPDPK:Q8SD18		GO:0006508: proteolysis	ECO:0000314:		P		Figure 1. SDS-Page and Mass Spec shows the size and boundaries of the genes cleaved by the prohead protease.	complete CACAO 11663
BPDPK:Q8SCY7		GO:0019082: viral protein processing	ECO:0000314:		P		Figure 5 shows "SDS-PAGE of an expression vector assay of the φKZ protease showing cleavage of φKZ head protein gp93."	complete CACAO 11660

References

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