4.A.6.1.1
The mannose (glucose, 2-deoxyglucose, glucosamine, N-acetylglucosamine, N-acetylmannosamine, mannosamine and fructose) PTS porter/group translocator, ManXYZ (Rephaeli and Saier 1980; Plumbridge 2015). Catalyzes xylose facilitated diffusion in lactobacilli. The order of D-sugar substrate affinities is: glucose > mannose > 2-deoxyglucose > N-acetylglucosamine > glucosamine > N-acetylmannosamine > mannosamine > fructose (Rephaeli and Saier 1980).  The mechanism appears to be rapid equilibrium, random, bi-bi sequential (Rephaeli and Saier 1980). L-sugars are not transported. This system is allostericallly inhibited by a complex of DicB (62 aas, P09557) and MinC (231 aas, P18186) (Jeckelmann and Erni 2020). At the transcriptional level, the manXYZ operon is regulated by the Mlc transcriptional regulator, and at the translational level it is regulated by the DicF small RNA that is complementary to manXYZ (Jeckelmann and Erni 2020). The 3-d structure of the IIC/IID complex revealed that the N- and C-terminal halves form the transport and scaffold domains, respectively (Liu et al. 2019).  Two 3-helix bundles are mixed by an intersubunit helix swap yielding tight intersubunit contacts with a novel fold. An "elevator" mechanism has been proposed in which the transport domain moves vertically or rotates relative to a stationary scaffold domain, where both the transport and scaffold domains consist of α-helices of both the IIC aqnd IID domains. Only the IIC and IID proteins, not hte IIAB protein are required for lambda phage infectivity (Esquinas-Rychen and Erni 2001).