Recombinant Gloeobacter violaceus Phosphate import ATP-binding protein PstB 2 (pstB2)

Introduction to Recombinant Gloeobacter violaceus Phosphate Import ATP-Binding Protein PstB 2 (PstB2)

The Recombinant Gloeobacter violaceus Phosphate import ATP-binding protein PstB 2 (PstB2) is a protein component of the ABC transporter complex PstSACB, which is involved in phosphate import in Gloeobacter violaceus . PstB2 is responsible for energy coupling to the transport system . ABC transporters are essential for the uptake of various nutrients, including phosphate, across cell membranes . Phosphate is crucial for all living organisms, playing a vital role in various cellular processes .

Gloeobacter violaceus and its Photosynthetic Apparatus

Gloeobacter violaceus is a cyanobacterium notable for lacking thylakoid membranes . Despite this absence, it performs photosystem II electron transport . Gloeobacter violaceus has a five-membered psbA gene family encoding three isoform variants of the PsbA (D1) reaction center protein of Photosystem II .

The Role of PstB in Phosphate Transport

The Pst system is crucial for phosphate uptake, especially under phosphate-limiting conditions . In the periplasm, complex phosphate is hydrolyzed via alkaline phosphatase, increasing the bioavailability of environmental phosphate sources . The Pst system is anchored into the inner cell membrane by PstC and PstA, forming a transmembrane channel that transports phosphate through the cytoplasmic membrane .

PstB2 in Nostoc punctiforme

Nostoc punctiforme has multiple Pst phosphate uptake systems across three distinct operons . Inactivation of pstB1 leads to alterations in the expression of pstB2, pstB3, and pstB4 to compensate for the deletion .

Pst Systems in Other Organisms

Synechocystis sp. strain PCC 6803 has two Pst systems (Pst1 and Pst2) that are differentially expressed depending on extracellular phosphate levels . Phosphate transport is primarily dependent on Pst1, with Pst2 contributing under low phosphate levels . Mycobacterium tuberculosis has two complete high-affinity Pst phosphate-specific transporters . PstA1 is essential for virulence and gene regulation, while PstA2 influences survival in acidic conditions .

psbA2 Gene and its Expression

The psbA2 gene (glr1706) in Gloeobacter violaceus encodes a Photosystem II protein D1 . While psbAI and psbAII dominate the psbA transcript pool under normal conditions, psbAIII is induced under high irradiance stress . psbAIV and psbAV, including psbA2, show consistent trace expression but are never quantitatively significant contributors to the psbA transcript pool .

Recombinant PstB2 Protein

Recombinant PstB2 protein is produced in E. coli with an N-terminal His tag to facilitate purification . The recombinant protein can be used for in vitro studies to understand its function and interactions with other components of the phosphate transport system .