Regulation of organophosphate metabolism in cyanobacteria. A review

Abstract

Cyanobacteria sense the environmental phosphate level and respond accordingly with the help of a two component regulatory system SphS SphR orthologous to PhoR PhoB of E. coli, where SphS act as a sensor kinase and SphR as a response regulator. Under phosphate limiting condition SphS SphR regulates the expression of many genes including genes which do not have the direct role in metabolism and transport of phosphate. Thus there is some crosstalk mechanism which connects this regulatory system to the other metabolic processes. Different types of enzymes and transporters are expressed by cyanobacteria under phos phate limitation to release and transport the phosphate from different organic compounds present in the envi ronment. Genes encoding these enzymes and transporters contain Pho boxes in their promoter region where SphR binds and regulate their expression under phosphate limitation. The machinery and mechanism of reg ulation is not uniform in cyanobacteria as it varies in different groups according to their evolutionary adapta tions. This review article is summarizing the reports on machinery and mechanism of organophosphate metabolism in cyanobacteria.

Differential Effects of Varying Concentrations of Phosphorus, Iron, and Nitrogen in N2-Fixing Cyanobacteria

“…When N abundance is low, 2-oxoglutarate (2-OG) may increase, and this could bind to a complex called PII-PipX and breaks this association, allowing the disassociation of PipX, and the formation of PipX-NtcA. PipX is a coactivator of NtcA, and it is suggested that it can stabilize NtcA and would help to recruit RNA polymerase (Tiwari et al, 2015;Kaushik et al, 2016;Giner-Lamia et al, 2017). PO 4 3− is represented as Pi.…”

Glyphosate dose modulates the uptake of inorganic phosphate by freshwater cyanobacteria

“…Species that fix atmospheric nitrogen increase its concentration in the soil. Cyanobacteria possess various environmental adaptations, including the ability to obtain all forms of phosphorus from the environment (Tiwari et al 2015 ; Lipok et al 2007 ). The secretion of enzymes responsible for the assimilation of phosphorus outside the cell is one of the ways to obtain this nutrient (Ravi and Balakumar 1998 ).…”

Estudo da biodegradação bacteriana do herbicida glifosato por microbiota de corpo hídrico e por coleção laboratorial e análise da presença de glifosato em corpo hídrico do município de Guaratinguetá/SP

“…Fósforo é o décimo primeiro elemento mais abundante na crosta terrestre, mas devido à sua alta reatividade, permanece indisponível aos microrganismos (TIWARI et al, 2015). Figura 3 -Organização proposta para os 14 polipeptídeos codificados pelo operon phn em E. coli.…”

“…Estudos posteriores da degradação de fosfonatos biogênicos identificaram quatro enzimas catabólicas principais e suas vias: C-P liase, fosfonoacetaldeído hidrolase (fosfonatase), fosfonoacetato hidrolase e fosfonopiruvato hidrolase, sendo glifosato degradado apenas pela primeira (VILLARREAL-CHIU et al, 2007). C-P liases e fosfonatases são as duas principais vias pelas quais moléculas de fosfonatos são metabolizados, sendo a primeira predominante entre os microrganismos (TIWARI et al, 2015). C-P liases são as únicas enzimas com reconhecida capacidade de quebrar as moléculas de glifosato e AMPA (SVIRIDOV et al, 2012).…”

“…Fosfonatos biogênicos são conhecidos desde 1959 (SVIRIDOV et al, 2012), amplamente distribuídos nos ecossistemas terrestres e aquáticos (TIWARI et al, 2015), comumente encontrados na forma de fosfonolipídeos, e podem ser usados como inibidores de enzimas, antibacterianos, antivirais, agentes antitumorais e herbicidas (METCALF;WANNER, 1991). Nos ecossistemas oceânicos, os fosfonatos são o segundo principal componente de fósforos orgânicos dissolvidos (25%), depois dos fosfoésteres, o que, provavelmente, levou bactérias e cianobactérias a adotar estratégias para utilizar fosfonatos como fonte de fósforo (TIWARI et al, 2015).…”