The LCP family or TagU family of proteins is a conserved
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
of
phosphotransferase
Phosphotransferases are a category of enzymes ( EC number 2.7) that catalyze phosphorylation reactions. The general form of the reactions they catalyze is:
:A-P + B \rightleftharpoons B-P + A
Where ''P'' is a phosphate group and A and B are the d ...
s that are involved in the attachment of
teichoic acid
Teichoic acids (''cf.'' Greek τεῖχος, ''teīkhos'', "wall", to be specific a fortification wall, as opposed to τοῖχος, ''toīkhos'', a regular wall) are bacterial copolymers of glycerol phosphate or ribitol phosphate and carbohyd ...
(TA) molecules to
gram-positive
In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall.
Gram-positive bac ...
cell wall or cell membrane. It was initially thought as the LytR (lytic repressor) component of a LytABC operon encoding
autolysin
Autolysins are endogenous lytic enzymes that break down the peptidoglycan components of biological cells which enables the separation of daughter cells following cell division. They are involved in cell growth, cell wall metabolism, cell division a ...
s, but the mechanism of regulation was later realized to be the production of TA molecules. It was accordingly renamed TagU.
The "LCP" acronym derives from three proteins initially identified to contain this domain, LytR (now TagU, ), cpsA ("Capsular polysaccharide expression regulator"), and psr ("PBP 5 synthesis repressor"). These proteins were mistaken as transcriptional regulators via different reasons, but all three of them are now known to be TagU-like enzymes. While TagU itself only attaches TA molecules to the peptidoglycan cell wall (forming WTA), other LCP proteins may glycosylate cell wall proteins (''A. oris'' LcpA, ) or attach TA molecules to a cell membrane anchor (forming LTA).
Most, if not all, LCP proteins also have a secondary pyrophosphatase activity.
Typical TagU proteins are made up of an N-terminal transmembrane domain (for anchoring), an optional, non-conserved accessory domain (CATH 3tflA01), a core catalytic domain, and sometimes a C-terminal domain for which the structure is unknown. The core LCP domain is a magnesium-dependent enzyme.
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References
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External links
MetaCyc RXN-18030
Polyisoprenyl-teichoic acid—peptidoglycan teichoic acid transferase
Acids
Cells
Enzymes
Proteins