Figure 1.

Global structure-function analysis of the Glycosyde Hydrolase 28 family. Numbers below the cartoons indicate the number of the separate helices or stacks. (A) Global architecture. Shown is chain B of 1CZF, endoPGI from A. niger. Gold: PB1 (stacks 3 to 12); red: PB2 (Stacks 2 to 12); green PB3 (Stacks 1 to 12). Black: Turn/Loop 1; Rose: Turn/Loop 2; Purple: Turn/Loop 3. The N-terminal part of the structure is supported by a single disulphide bridge (SS1), two disulphide bridges (SS3 and 4) support the C terminal part of the structure, one in Loop 1–12 and a second in the thirteenth and last stack. A fourth disulphide bridge (SS2) in Turn 3-7 supports the catalytic site that is located approximately in the centre of the slide (Turns 3-6 to 3-8). Disulphide bridges and catalytic residues are in black and blue sticks, respectively. (B,C) Structural alignment of endoPGs 1CZF, 1NHC, 1HG8 and 1KCD. RMSDs in Å indicate the structural dissimilarity with reference 1CZF. In blue stick are the two galacturonates co-crystallized with 1KCD. D180, D183, D200, D201 and H223 and corresponding residues in other structures are in red stick; (C) H bonding of galacturonates to N91, Q120, H150, D153, S201, R226, K228 and Y262 (1CZF) and corresponding residues (stick with colour according to the structure). (D) Structural alignment of endoPG 1CZF, endoRG 1RMG and endoXG 4C2L. Details as in (B); (E) Sequence conservation logo of GH28 superfamily region 171–231. Indicated are the highly conserved aspartates and H223, numbers according to 1CZF.