5hi8

Publication Abstract from PubMed

Auxiliary metabolic genes (AMG) are commonly found in the genomes of phages that infect cyanobacteria and increase cyanophage's fitness. AMGs are often homologs of host genes, and also typically related to photosynthesis. For example, the thetacpeT gene in the cyanophage P-HM1 encodes a putative phycobiliprotein lyase related to cyanobacterial T-type lyases, which facilitate attachment of linear tetrapyrrole chromophores to Cys-155 of phycobiliprotein beta-subunits, suggesting that thetaCpeT may also help assemble light-harvesting phycobiliproteins during infection. In order to investigate this possibility, we structurally and biochemically characterized recombinant thetaCpeT. The solved crystal structure of thetaCpeT at 1.8 A resolution revealed that the protein adopts a similar fold as the cyanobacterial T-type lyase CpcT from Nostoc sp. PCC7120 but overall is more compact and smaller. thetaCpeT specifically binds phycoerythrobilin (PEB) in vitro leading to a tight complex that can also be formed in Escherichia coli when it is co-expressed with genes encoding PEB biosynthesis (i.e. ho1 and pebS). The formed thetaCpeT:PEB complex was very stable as the chromophore was not lost during chromatography and displayed a strong red fluorescence with a fluorescence quantum yield of thetaF=0.3. This complex was not directly able to transfer PEB to the host phycobiliprotein beta-subunit. However, it could assist the host lyase CpeS in its function by providing a pool of readily available PEB, a feature that might be important for fast phycobiliprotein assembly during phage infection.

Auxiliary metabolic genes- Distinct Features of Cyanophage-encoded T-type Phycobiliprotein Lyase thetaCpeT.,Gasper R, Schwach J, Hartmann J, Holtkamp A, Wiethaus J, Riedel N, Hofmann E, Frankenberg-Dinkel N J Biol Chem. 2017 Jan 10. pii: jbc.M116.769703. doi: 10.1074/jbc.M116.769703. PMID:28073912^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.