Levansucrase/Invertase. This Pfam family consists of the glycosyl hydrolase 68 family, including several bacterial levansucrase enzymes, and invertase from zymomonas.

Glycosyl hydrolase family 68, includes levansucrase, beta-fructofuranosidase and inulosucrase. Glycosyl hydrolase family 68 (GH68) consists of frucosyltransferases (FTFs) that include levansucrase (EC 2.4.1.10), beta-fructofuranosidase (EC 3.2.1.26) and inulosucrase (EC 2.4.1.9), all of which use sucrose as their preferential donor substrate. Levansucrase, also known as beta-D-fructofuranosyl transferase, catalyzes the transfer of the sucrose fructosyl moiety to a growing levan chain. Similarly, inulosucrase catalyzes long inulin-type of fructans, and beta-fructofuranosidases create fructooligosaccharides (FOS). However, in the absence of high fructan/sucrose ratio, some GH68 enzymes can also use fructan as donor substrate. GH68 retaining enzymes (i.e. they retain the configuration at anomeric carbon atom of the substrate) catalyze hydrolysis in two steps involving a covalent glycosyl enzyme intermediate: an aspartate located close to the N-terminus acts as the catalytic nucleophile and a glutamate acts as the general acid/base; a conserved aspartate residue in the Arg-Asp-Pro (RDP) motif stabilizes the transition state. A common structural feature of all these enzymes is a 5-bladed beta-propeller domain, similar to GH43, that contains the catalytic acid and catalytic base. A long V-shaped groove, partially enclosed at one end, forms a single extended substrate-binding surface across the face of the propeller. Biotechnological applications of these enzymes include use of inulin in inexpensive production of rich fructose syrups as well as use of FOS as health-promoting pre-biotics.

Glucan-binding domain (YG repeat) [Carbohydrate transport and metabolism].

pneumococcal surface protein A. The pneumococcal surface protein proteins, found in Streptococcus pneumoniae, are repetitive, with patterns of localized high sequence identity across pairs of proteins given different specific names that recombination may be presumed. This protein, PspA, has an N-terminal region that lacks a cross-wall-targeting YSIRK type extended signal peptide, in contrast to the closely related choline-binding protein CbpA which has a similar C-terminus but a YSIRK-containing region at the N-terminus.

pneumococcal surface protein PspC, choline-binding form. The pneumococcal surface protein PspC, as described in Streptococcus pneumoniae, is a repetitive and highly variable protein, recognized by a conserved N-terminal domain and also by genomic location. This form, subgroup 1, has variable numbers of a choline-binding repeat in the C-terminal region, and is also known as choline-binding protein A. The other form, subgroup 2, is anchored covalently after cleavage by sortase at a C-terminal LPXTG site.

Crystalstructure of inulosucrase from Lactobacillus johnsonii NCC533 [Lactobacillus johnsonii],2YFT_A Crystal structure of inulosucrase from Lactobacillus johnsonii NCC533 in complex with 1-kestose [Lactobacillus johnsonii]

Crystalstructure of inulosucrase from Lactobacillus johnsonii NCC533 in complex with sucrose [Lactobacillus johnsonii]

ChainA, Levansucrase [Priestia megaterium],3OM4_B Chain B, Levansucrase [Priestia megaterium],3OM4_C Chain C, Levansucrase [Priestia megaterium],3OM4_D Chain D, Levansucrase [Priestia megaterium]

ChainA, Levansucrase [Priestia megaterium],3OM6_B Chain B, Levansucrase [Priestia megaterium],3OM6_C Chain C, Levansucrase [Priestia megaterium],3OM6_D Chain D, Levansucrase [Priestia megaterium]

ChainA, Levansucrase [Priestia megaterium],3OM7_B Chain B, Levansucrase [Priestia megaterium],3OM7_C Chain C, Levansucrase [Priestia megaterium],3OM7_D Chain D, Levansucrase [Priestia megaterium]

Inulosucrase OS=Lactobacillus gasseri OX=1596 GN=inuGB PE=1 SV=1

Inulosucrase OS=Lactobacillus johnsonii (strain CNCM I-12250 / La1 / NCC 533) OX=257314 GN=inuJ PE=1 SV=1

Levansucrase OS=Streptococcus mutans serotype c (strain ATCC 700610 / UA159) OX=210007 GN=ftf PE=3 SV=2

Levansucrase OS=Lactobacillus gasseri OX=1596 GN=levG PE=1 SV=1

Levansucrase OS=Fructilactobacillus sanfranciscensis OX=1625 GN=levS PE=1 SV=1