Structure of GlgS. (A) The backbone superposition of the 15 lowest-energy structures generated with MOLMOL [26]. The superposition was done using region Ser4-Leu62. (B) Ribbon representation of the GlgS structure generated with MOLSCRIPT [27] and Raster3D [28]. N- and C-termini and α-helices are labeled. (C) Enlarged view of residues that form hydrophobic core (in purple), are potentially involved in the function (in green), and which mutations knocked-out GlgS activity (in red). Phe45 also is a part of the hydrophobic core. The residues shown are labeled with a one-letter name code and a residue number. The figure was generated with MOLMOL [26]. (D) Surface charge distribution suggests importance of charged interactions for GlgS function. The protein side with more charges contains Ser17, which is essential for functionality. Positively charged residues are shown in blue, negatively charged residues in red. The figure was generated with GRASP [29].

GlgS is highly conserved in enterobacteria. The aligned sequences represent GlgS from Escherichia coli K12 (E. coli K12; gi:1789428), Escherichia coli O157 (E. coli O157; gi:13363404), Shigella flexneri (Sh. flexneri; gi:30042655), Salmonella enterica serovar Typhi (S. enterica; gi:16504274), and Salmonella typhimurium (S. typhimurium; gi:20138181). The secondary structure elements refer to GlgS from Escherichia coli.

GlgS is structurally similar to a fragment from the tetratricopeptide repeats domain from protein phosphatase 5. (A) Ribbon representation of the backbone superposition of GlgS and TPRD using 38 residues results in root mean square deviation of 2.0 Å. GlgS is shown in red, TPRD in cyan. The figure was generated using MOLSCRIPT [27] and Raster3D [28]. (B) Sequence alignment of TPRD and GlgS with secondary structure elements shown. Homologous residues are in bold.