The Role of Proline in Energy Metabolism

Bursell, E.

doi:10.1007/978-1-4615-9221-1_5

Cited by 83 publications

(86 citation statements)

References 76 publications

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“…Each strain was crossed to MB1057, and meiotic products were used for mapping the location of the integration event. All three PU72-lacZ genes showed tight linkage to the chromosome VIII marker, thrl (PUT2-lacZ14, 9 parental ditypes, 0 nonparental ditypes, 1 tetratype; PUT2-lacZJ24, 16 parental ditypes, 0 nonparental ditypes, 0 tetratypes; PUT2-lacZ366, 13 parental ditypes, 0 nonparental ditypes 0 tetratypes and were therefore present in tandem with a wild-type copy of the PUT2 gene.…”

Section: Methodsmentioning

confidence: 99%

“…Proline serves as a source of nitrogen by its conversion to glutamate, a process requiring a functional electron transport chain (13). Like the pathways in mammalian liver (38), insect flight muscle (16), and plant cells (8), the yeast enzymes are associated with the mitochondria (15). We have cloned (12), sequenced (40), and characterized (12)(13)(14) the expression of the PUT2 gene which encodes A1-pyrroline-5-carboxylate (PSC) dehydrogenase, the second enzyme in the pathway.…”

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confidence: 99%

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Amino-terminal fragments of delta 1-pyrroline-5-carboxylate dehydrogenase direct beta-galactosidase to the mitochondrial matrix in Saccharomyces cerevisiae.

Brandriss¹,

Krzywicki²

1986

Mol. Cell. Biol.

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Al-Pyrroline-5-carboxylate (P5C) dehydrogenase, the second enzyme in the proline utilization (Put) pathway of Saccharomyces cerevisiae and the product of the PUT2 gene, was localized to the matrix compartment by a mitochondrial fractionation procedure. This result was confirmed by demonstrating that the enzyme had limited activity toward an externally added substrate that could not penetrate the inner mitochondrial membrane (latency). To learn more about the nature of the import of this enzyme, three gene fusions were constructed that carried 5'-regulatory sequences through codons 14, 124, or 366 of the PUT2 gene ligated to the lacZ gene of Escherichia coli. When these fusions were introduced into S. cerevisiae either on multicopy plasmids or stably integrated into the genome, proline-inducible I-galactosidase was made. The shortest gene fusion, PUT2-lacZ14, caused the production of a high level of I-galactosidase that was found exclusively in the cytoplasm. The PUT2-lacZ124 and PUT2-lacZ366 fusions made lower levels of ,-galactosidases that were mitochondrially localized. Mitochondrial fractionation and protease-protection experiments showed that the PUT2-lacZ124 hybrid protein was located exclusively in the matrix, while the PUT2-lacZ366 hybrid was found in the matrix as well as the inner membrane. Thus, the amino-terminal 124 amino acids of P5C dehydrogenase carries sufficient information to target and deliver I-galactosidase to the matrix compartment. The expression of the longer hybrids had deleterious effects on cell growth; PUT2-lacZ366-containing strains failed to grow on proline as the sole source of nitrogen. In the presence of the longest hybrid ,-galactosidase, the wild-type P5C dehydrogenase was still properly localized in the matrix compartment, but its activity was reduced. The nature of the effects of these hybrid proteins on cell growth is discussed.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Amino-terminal fragments of delta 1-pyrroline-5-carboxylate dehydrogenase direct beta-galactosidase to the mitochondrial matrix in Saccharomyces cerevisiae.

Brandriss¹,

Krzywicki²

1986

Mol. Cell. Biol.

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“…In these parasite forms, the active transport of glucose, L-proline, or L-glutamic acid has been previously demonstrated (2,24,25,29). With regard to L-proline, which is one of the prominent constituents of the hemolymph and tissue fluids of hematophagous insect vectors (1,6), its uptake by active proline transport systems has been found in epimastigotes (24) and in tissue culture trypomastigotes that correspond to the bloodstream parasites and intracellular epimastigotes and amastigotes (30). Concerning the metacyclic trypomastigotes, which are found in the terminal portions of the digestive tract of triatomine insects and constitute the parasite forms responsible for the initial interaction with host cells, there is no information regarding whether they transport and utilize as an energy source the compounds referred to above.…”

mentioning

confidence: 99%

Use of l -Proline and ATP Production by Trypanosoma cruzi Metacyclic Forms as Requirements for Host Cell Invasion

et al. 2009

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The process of host cell invasion by Trypanosoma cruzi depends on parasite energy. What source of energy is used for that event is not known. To address this and other questions related to T. cruzi energy requirements and cell invasion, we analyzed metacyclic trypomastigote forms of the phylogenetically distant CL and G strains. For both strains, the nutritional stress experienced by cells starved for 24, 36, or 48 h in phosphatebuffered saline reduced the ATP content and the ability of the parasite to invade HeLa cells proportionally to the starvation time. Inhibition of ATP production by treating parasites with rotenone plus antimycin A also diminished the infectivity. Nutrient depletion did not alter the expression of gp82, the surface molecule that mediates CL strain internalization, but increased the expression of gp90, the negative regulator of cell invasion, in the G strain. When L-proline was given to metacyclic forms starved for 36 h, the ATP levels were restored to those of nonstarved controls for both strains. Glucose had no such effect, although this carbohydrate and L-proline were transported in similar fashions. Recovery of infectivity promoted by L-proline treatment of starved parasites was restricted to the CL strain. The profile of restoration of ATP content and gp82-mediated invasion capacity by L-proline treatment of starved Y-strain parasites was similar to that of the CL strain, whereas the Dm28 and Dm30 strains, whose infectivity is downregulated by gp90, behaved like the G strain. L-Proline was also found to increase the ability of the CL strain to traverse a gastric mucin layer, a property important for the establishment of T. cruzi infection by the oral route. Efficient translocation of parasites through gastric mucin toward the target epithelial cells in the stomach mucosa is an essential requirement for subsequent cell invasion. By relying on these closely associated ATP-driven processes, the metacyclic trypomastigotes effectively accomplish their internalization.Host cell invasion by Trypanosoma cruzi, which is critical for the establishment of infection in mammalian hosts, is a multistep process involving various parasite and host cell molecules that, in a concerted series of events, leads to intracellular Ca 2ϩ mobilization in both types of cells (5,12,32). The first step of this process, namely, T. cruzi attachment to target cells, requires parasite energy (23). The main source of energy for this event is unknown. Also unknown is whether there are differences in energy requirements among different T. cruzi strains that use distinct mechanisms to enter target cells.Epimastigotes, the proliferative and noninfective developmental forms of T. cruzi, use mainly glucose, L-proline, and L-glutamic acid as carbon sources and to obtain energy through respiration (27). In these parasite forms, the active transport of glucose, L-proline, or L-glutamic acid has been previously demonstrated (2,24,25,29). With regard to L-proline, which is one of the prominent constituents of the hemolymph and t...

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“…This procyclic metabolism parallels the use of proline as an important energy source in the flight metabolism of the tsetse fly (8). The presence of an abundant proline-and glutamic acid-rich protein in procyclic trypanosomes is intriguing in this context.…”

Section: Discussionmentioning

confidence: 89%

“…It is notable that procyclic trypanosomes metabolize proline rapidly and in preference to glucose (14,42) and, further, that glutamic acid is one of the intermediates in proline catabolism (8). This procyclic metabolism parallels the use of proline as an important energy source in the flight metabolism of the tsetse fly (8).…”

Section: Discussionmentioning

confidence: 99%

Developmental regulation of a novel repetitive protein of Trypanosoma brucei.

Mowatt¹,

Clayton²

1987

Mol. Cell. Biol.

129

133

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Trypanosoma brucei undergoes many morphological and biochemical changes during transformation from the bloodstream trypomastigote to the insect procyclic trypomastigote form. We cloned and determined the complete nucleotide sequence of a developmentally regulated cDNA. The corresponding mRNA was abundant in in vitro-cultivated procyclics but absent in bloodstream forms. The trypanosome genome contains eight genes homologous to this cDNA, arranged as four unlinked pairs of tandem repeats. The longest open reading frame of the cDNA predicts a protein of 15 kilodaltons, the central portion of which consists of 29 tandem glutamate-proline dipeptides. The repetitive region is preceded by an amino-terminal signal sequence and followed by a hydrophobic domain that could serve as a membrane anchor; the mRNA was found on membrane-bound polyribosomes. These results suggest that the protein is membrane associated.

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The Role of Proline in Energy Metabolism

Cited by 83 publications

References 76 publications

Amino-terminal fragments of delta 1-pyrroline-5-carboxylate dehydrogenase direct beta-galactosidase to the mitochondrial matrix in Saccharomyces cerevisiae.

Amino-terminal fragments of delta 1-pyrroline-5-carboxylate dehydrogenase direct beta-galactosidase to the mitochondrial matrix in Saccharomyces cerevisiae.

Use of l -Proline and ATP Production by Trypanosoma cruzi Metacyclic Forms as Requirements for Host Cell Invasion

Developmental regulation of a novel repetitive protein of Trypanosoma brucei.

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