TY - JOUR

T1 - Enzymatic systems of inorganic pyrophosphate bioenergetics in photosynthetic and heterotrophic protists

T2 - Remnants or metabolic cornerstones?

AU - Perez-Castiñeira, Jose R.

AU - Gómez-García, Rosario

AU - López-Marqués, Rosa L.

AU - Losada, Manuel

AU - Serrano, Aurelio

N1 - Funding Information: Acknowledgements This work was supported by grant PB 97-1135 from DGICYT (MCYT, Spain) and by Grupo PAI CVI-0261 (Junta de Andalucṍ a). Work on PPases of parasitic protists has been performed in collaboration with th e groups of Drs. L.M. Ruiz-Pérez and D. González-Pacanowska (Instituto de Parasito-logṍ a y Biomedicina ``López-Neyra'', CSIC, Granada, Spain) and Dr. Jorge Alvar (Centro Nacional de Microbiologṍ a, Instituto de Salud Carlos III, Madrid, Spain). Thanks are due to Dr. A. Torres (University of Seville) for DNA samples of some ciliates. Some preliminary sequence data were obtained from the microbial genome websites of NCBI and TIGR. Gene sequences obtained in the authors' laboratory have been submitted to databases and most of them are under confidential status until publication. Several publications on the topics described here are in preparation.

PY - 2001

Y1 - 2001

N2 - An increasing body of biochemical and genetic evidence suggests that inorganic pyrophosphate (PPi) plays an important role in protist bioenergetics. In these organisms, two types of inorganic pyrophosphatases [EC 3.6.1.1, namely soluble PPases (sPPases) and proton-translocating PPases (H+-PPases)] that hydrolyse the PPi generated by cell anabolism, thereby replenishing the orthophosphate pool needed for phosphorylation reactions, are present in different cellular compartments. Photosynthetic and heterotrophic protists possess sPPases located in cellular organelles (plastids and mitochondria), where many anabolic and biosynthetic reactions take place, in addition to H + PPases, which are integral membrane proteins of the vacuolysosomal membranes and use the chemical energy of PPi to generate an electrochemical proton gradient useful in cell bioenergetics. This last category of proton pumps was considered to be restricted to higher plants and some primitive photosynthetic bacteria, but it has been found recently in many protists (microalgae and protozoa) and bacteria, thus indicating that H+-PPases are much more widespread than previously thought. No cytosolic sPPase (in bacteria, fungi and animal cells) has been shown to occur in these lower eukaryotes. The widespread occurrence of these key enzymes of PPi metabolism among evolutionarily divergent protists strongly supports the ancestral character of the bioenergetics based on this simple energy-rich compound, which may play an important role in survival under different biotic and abiotic stress conditions.

AB - An increasing body of biochemical and genetic evidence suggests that inorganic pyrophosphate (PPi) plays an important role in protist bioenergetics. In these organisms, two types of inorganic pyrophosphatases [EC 3.6.1.1, namely soluble PPases (sPPases) and proton-translocating PPases (H+-PPases)] that hydrolyse the PPi generated by cell anabolism, thereby replenishing the orthophosphate pool needed for phosphorylation reactions, are present in different cellular compartments. Photosynthetic and heterotrophic protists possess sPPases located in cellular organelles (plastids and mitochondria), where many anabolic and biosynthetic reactions take place, in addition to H + PPases, which are integral membrane proteins of the vacuolysosomal membranes and use the chemical energy of PPi to generate an electrochemical proton gradient useful in cell bioenergetics. This last category of proton pumps was considered to be restricted to higher plants and some primitive photosynthetic bacteria, but it has been found recently in many protists (microalgae and protozoa) and bacteria, thus indicating that H+-PPases are much more widespread than previously thought. No cytosolic sPPase (in bacteria, fungi and animal cells) has been shown to occur in these lower eukaryotes. The widespread occurrence of these key enzymes of PPi metabolism among evolutionarily divergent protists strongly supports the ancestral character of the bioenergetics based on this simple energy-rich compound, which may play an important role in survival under different biotic and abiotic stress conditions.

KW - Inorganic pyrophosphate soluble inorganic pyrophophatase proton

KW - Translocating pyrophosphatase photosynthetic protists parasitic protists

UR - http://www.scopus.com/inward/record.url?scp=0035469221&partnerID=8YFLogxK

U2 - 10.1007/S10123-001-0028-X

DO - 10.1007/S10123-001-0028-X

M3 - Journal article

C2 - 11820431

AN - SCOPUS:0035469221

VL - 4

SP - 135

EP - 142

JO - International Microbiology

JF - International Microbiology

SN - 1139-6709

IS - 3

ER -