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Fig. 8 | BMC Bioinformatics

Fig. 8

From: Phage spanins: diversity, topological dynamics and gene convergence

Fig. 8

a: Primary structure analysis of the separated spanins pseT.3 (i-spanin) and pseT.2 (o-spanin) from T4. Unlike the traditional lysis cassette as in lambda, these genes are not located near the T4 holin (t) and endolysin (e). The inset shows the predicted primary structures of PseT.3 and PseT.2 with their TMD and signal sequence highlighted in gray and green, respectively. pseT.3 (black) encodes a 117 aa i-spanin and pseT.2 encodes an 83aa o-spanin. The T4 o-spanin has a predicted helix at the C-terminus and is comparatively larger than the o-spanin in lambda which lacks any predicted or detected helical structure. The position of predicted coiled coil structures in the i-spanin are shown by open rectangles. The two periplasmic cysteines in PseT.2, at positions 87 and 98 are shown by arrows. b: Lysis profiles of T4 spanin cysteine mutants. MC4100 (λ900RzamRz1am) lysogens grown in LB supplemented with 10 mM MgCl2, carrying the following plasmids, were induced at time = 0 and growth was monitored at A550: pRE (−X-); pRzRz1 (−■-); ppseT.3pseT.2 (−-); ppseT.3pseT.2C87S (−□-); ppseT.3pseT.2C98S (−Δ-); ppseT.3pseT.2C87,982S (−-). c, d: Western blot analysis of T4 spanin cysteine mutants: TCA precipitates from induced MC4100 (λ900RzamRz1am) lysogens carrying the indicated allele were prepared and analyzed in the absence or presence of β-mercaptoethanol as indicated above the gel. For each analysis, the spanin antibody used is indicated at the bottom of each panel. The location of monomeric and dimeric species of PseT.3 and PseT.2 are indicated by (single asterisk) and (double asterisk). Additionally, putative degradation products are indicated by square on the right of each blot. Filled triangles indicate a background band. The alleles are indicated above each lane. Molecular markers in kDa are indicated to the left

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