FIG 1.

Structure of K1L1 and domain organization of Spt5. (A) The crystal structure of K1L1 comprises a Tudor domain barrel encompassing most of the KOW region and an insertion domain with a novel fold formed mainly from the Linker1 region. The N and C termini of K1L1 correspond to L382 and F508, respectively. A disordered region (I428 to R438) is found between the indicated residues E427 and R439. (B) Secondary-structure diagram drawn from the K1L1 structure and colored similarly to panel A. α-Helices are shown as cylinders, β-strands as block arrows, and loops as solid lines. (C) Updated KOW1 consensus sequence modified from the previous KOW1 consensus shown in Fig. S2B in the supplemental material. L1 is marked at its inserted position within K1. (D) Updated Spt5 domain organization with the K1L1 region delineated according to the crystal structure, modified from Fig. S2A in the supplemental material.