Structure similarities with bacteria binding proteins

Thiamin transport has been nearly exclusively studied in mammalian cells. However, a few studies carried out in bacteria show that thiamin can be transported via ABC transporters. These transporters comprise a periplasmic thiamin binding protein in gram-negative bacteria such as E. coli and Salmonella typhimurium. These proteins are generally not specific for thiamin as they also bind ThMP and ThDP. Examination of the three-dimensional structure of an E. coli thiamin binding protein revealed structural similarities with thiami-nase I, suggesting a common ancestor (Soriano et al. 2008). 

Many larger lipid carrier proteins are known. The 476-residue plasma cholesteryl ester transfer protein is discussed briefly in Chapter 22. Plasma phospholipid transfer proteins are of similar size.t/U A 456-residue human phospholipid-binding protein interacts with the lipopolysaccharide of the surfaces of gram-negative bacteria (Fig. 8-30) and participates in the immune response to the bacteria. It has an elongated boomerang shape with two cavities, both of which bind a molecule of phosphatidylcholine. Other plasma lipid transfer proteins may have similar structures/... 

As noted in Section 3, some pathogenic bacteria have transferrin receptors on their outer membranes to acquire diferric transferrin from their host. These outer membrane receptors extract the iron from the transferrin and transport it into the periplasm where it is picked up by the periplasmic ferric binding proteins (Fbp), which carry the iron to a transmembrane protein in the inner membrane that conveys it into the cytoplasm. A considerable amount of chemical and structural information has been gathered for Fbp, which is sometimes referred to as bacterial transferrin in recognition of its similarities with animal transferrin. ... 

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