Sugar transporter proteins

Wood IS, Trayhurn P (2003) Glucose transporters (GLUT and SGLT) expanded families of sugar transport proteins. BrJNutr 89 3-9... 

Plasmid-mediated resistance to QACs and chlorhexidine in S. aureus has been cloned in E. coli [302] but the level of resistance is low and the mechanism not fully elucidated. The efflux-mediated antiseptic resistance gene qacA from S. aureus has a common ancestry with tetracycline- and sugar-transported proteins [227-229]. 

Amino acids involved in binding M6P are shown in O Fig. 8. The phosphate moiety is coordinated by His 105, Asn 104, Asp 103 and divalent cation. Each hydroxyl of Man is hydrogen-bonded to binding site residues, while no interactions between the hydrophobic carbohydrate backbone and aromatic side chains are observed [148]. The multiple contacts between lectin and M6P, in contrast to that observed for many lectins which mediate cell surface interactions, are reflected in pM binding constants, reminiscent of bacterial arabinose-binding protein which functions as a sugar transport protein [149]. 

Sugars Lectins, glycosidases, sugar transporter proteins... 

Rouch DA, Cram DS. DiBerardino D, LictUiohn TG. Skuttay RA. Efflux-mediated antiseptic resistance gene qocA from Su Aylococcus aureus Common ancestry with cecracycline and sugar-transport proteins. Mol Microbiol 1990 4 2051—7062-... 

Several unique features distinguish the phosphotransferase. First, phos-phoenolpyruvate is both the phosphoryl donor and the energy source for sugar transport. Second, four different proteins are required for this transport. Two of these proteins (Enzyme I and HPr) are general and are required for the phosphorylation of all PTS-transported sugars. The other two proteins (Enzyme II and Enzyme III) are specific for the particular sugar to be transported. 

Antibiotics are produced by fermentation. The process may take a few days to obtain an extractable amount of product. Antibiotic production is done by the batch process. Oxygen transport is the major concern therefore sufficient polymeric sugar and protein with a trace amount of elemental growth factors are used to enhance production. An anti-biogram test is used to observe the amount of antimicrobial agent in the fermentation broth. A bioassay determines the activity unit of the bactericides. 

Although cytochalasin B normally functions as a reversible inhibitor of glucose transport, upon exposure to ultraviolet light a small proportion of the bound cytochalasin B molecules become covalently linked to the transporter protein [128-130]. Photolabelling is inhibitable by D-glucose and other transported sugars but not by... 

The lactose transporter (lac permease) of E. coli is without doubt the most intensively studied and best understood of the bacterial proton-linked sugar transporters. Since its sequence was reported in 1980 [233] prodigious efforts have been made to elucidate its molecular mechanism by site-directed mutagenesis and other means. These studies have recently been reviewed elsewhere [234,235] and so will not be discussed in detail here. The important question for the present Chapter is whether the protein is related to the sugar-transporter family and so has lessons to teach us about their mechanisms. The permease is a 417-residue protein, and, like the other... 

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