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Structure of the month - December 2013

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Table 1.

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Figure 1.

Structure of the SynCph2(1-2) photosensor. (A) Domain organization of SynCph1 and SynCph2. The tonguelike regions protruding from the GAF2 and PHY domains are shown in green and purple, respectively; the knot in SynCph1 as black lines. SynCph1 and SynCph2 differ in their effector domains: a histidine kinase domain (HKD) and cdiGMP turn-over (GGDEF and EAL) and regulatory (GGDEF*) domains. (B) Crystal structure of the SynCph2(1-2) module. GAF2 (green) contains a tonguelike region (dark-green) for sealing the PCB (cyan)-binding pocket. The GAF1 domain is in orange.

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Figure 10.

A model for the Trp-motif switch within phytochromes. Upon red-light triggered formation of the Pfr state and breakage of the tongue/GAF1 Asp-Arg salt bridge (inlet) the tip of the tongue refolds with concomitant disordering of the stalk-like -hairpin and formation of an Asp-Ser salt bridge (inlet).