Fig. 1: Conserved surfaces on SPOC mediate phosphoserine binding. | Nature Communications

Fig. 1: Conserved surfaces on SPOC mediate phosphoserine binding.

From: The SPOC domain is a phosphoserine binding module that bridges transcription machinery with co- and post-transcriptional regulators

Fig. 1: Conserved surfaces on SPOC mediate phosphoserine binding.The alternative text for this image may have been generated using AI.

a Multiple sequence alignment of human SPOC domains based on PROMALSD3 using SPOC structures from human SHARP (2RT5), human PHF3 (6Q2V) and sequences from human RBM15, RBM15B, DIDO and SPOCD1. Colored squares indicate conserved residues that constitute basic patches on the surface of SPOC. The patches are marked in the same colors in (b–f). A red asterisk indicates an arginine residue that is conserved in all human SPOC domains except SPOCD1. Secondary structure elements are indicated above the primary sequence. b Crystal structure of PHF3 SPOC in complex with 2×S2P CTD peptide (6IC8). Conserved basic patches that mediate binding to phosphorylated CTD residues are indicated with green circles. The distance between the patches is 24 Å. c NMR solution structure of SHARP SPOC in complex with phosphorylated SMRT peptide (2RT5). The yellow circle indicates the conserved basic patch that coordinates binding to SMRT pS2522. d AlphaFold2 structural model DIDO SPOC (Q9BTC0). Green circles indicate conserved surface patches. The distance between the patches is 21 Å. e Crystal structure of RBM15 SPOC (7Z27). Colored circles indicate the conserved basic surface patch (patch 1, yellow) and a potential second patch (patch 2, orange). The distance between the patches is 21 Å. f AlphaFold2 structural model of SPOCD1 SPOC (Q6ZMY3). The surface patches indicated by green circles are only partially conserved and display a less pronounced positive charge. The distance between the patches is 36 Å. g Structural model of the interaction between RBM15 SPOC and serine-5-phosphorylated CTD generated in PyMOL and refined using the HADDOCK2.2 webserver28,29. All SPOC domains are shown in the same orientation and at the same scale. Electrostatic surface potential in (b–f) was calculated using the Coulombic Surface Coloring tool in UCSF Chimera60 and is depicted ranging from −10 (red) to +10 (blue) kcal/(mol*e). The distances in (b) and (d–f) are given as the mean distance between the terminal atoms of the amino acids making up the basic patches and were measured using the structure measurements—distances tool in UCSF Chimera.

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