The Trk Potassium Transporter Is Required for RsmB-Mediated Activation of Virulence in the Phytopathogen Pectobacterium wasabiae

Pectobacterium wasabiae (previously known as Erwinia carotovora) is an important plant pathogen that regulates the production of plant cell wall-degrading enzymes through an N-acyl homoserine lactone-based quorum sensing system and through the GacS/GacA two-component system (also known as ExpS/ExpA). At high cell density, activation of GacS/GacA induces the expression of RsmB, a noncoding RNA that is essential for the activation of virulence in this bacterium. A genetic screen to identify regulators of RsmB revealed that mutants defective in components of a putative Trk potassium transporter (trkH and trkA) had decreased rsmB expression. Further analysis of these mutants showed that changes in potassium concentration influenced rsmB expression and consequent tissue damage in potato tubers and that this regulation required an intact Trk system. Regulation of rsmB expression by potassium via the Trk system occurred even in the absence of the GacS/GacA system, demonstrating that these systems act independently and are both required for full activation of RsmB and for the downstream induction of virulence in potato infection assays. Overall, our results identified potassium as an essential environmental factor regulating the Rsm system, and the consequent induction of virulence, in the plant pathogen P. wasabiae.

Adaptation of yeasts to fructose rich environments: a role for horizontal gene transfer of a fructose transporter

Abstract of the poster presented 33rd Small Meeting on Yeast Transport and Energetics, 21-24 July 2015, Lisbon, Portugal.

Stepwise functional evolution in the Ffz sugar transporter family

Abstract of the poster presented at the Microbiotec’15 Congress, 10-12 December 2015, University of Évora, Portugal.

LeProT1, a Transporter for Proline, Glycine Betaine, and γ-Amino Butyric Acid in Tomato Pollen

During maturation, pollen undergoes a period of dehydration accompanied by the accumulation of compatible solutes.Solute import across the pollen plasma membrane, which occurs via proteinaceous transporters, is required to support pollen development and also for subsequent germination and pollen tube growth. Analysis of the free amino acid composition of various tissues in tomato revealed that the proline content in flowers was 60 times higher than in any other organ analyzed. Within the floral organs, proline was confined predominantly to pollen, where it represented >70 of total free amino acids. Uptake experiments demonstrated that mature as well as germinated pollen rapidly take up proline. To identify proline transporters in tomato pollen, we isolated genes homologous to Arabidopsis proline transporters. LeProT1 was specifically expressed both in mature and germinating pollen, as demonstrated by RNA in situ hybridization. Expression in a yeast mutant demonstrated that LeProT1 transports proline and γ-amino butyric acid with low affinity and glycine betaine with high affinity. Direct uptake and competition studies demonstrate that LeProT1 constitutes a general transporter for compatible solutes.

Knock-out of Arabidopsis metal transporter gene IRT1 results in iron deficiency accompanied by cell differentiation defects

IRT1 and IRT2 are members of the Arabidopsis ZIP metal transporter family that are specifically induced by iron deprivation in roots and act as heterologous suppressors of yeast mutations inhibiting iron and zinc uptake. Although IRT1 and IRT2 are thought to perform redundant functions as root-specific metal transporters, insertional inactivation of the IRT1 gene alone results in typical symptoms of iron deficiency causing severe leaf chlorosis and lethality in soil. The irt1 mutation is characterized by specific developmental defects, including a drastic reduction of chloroplast thylakoid stacking into grana and lack of palisade parenchyma differentiation in leaves, reduced number of vascular bundles in stems, and irregular patterns of enlarged endodermal and cortex cells in roots. Pulse labeling with 59Fe through the root system shows that the irt1 mutation reduces iron accumulation in the shoots. Short-term labeling with 65Zn reveals no alteration in spatial distribution of zinc, but indicates a lower level of zinc accumulation. In comparison to wild-type, the irt1 mutant responds to iron and zinc deprivation by altered expression of certain zinc and iron transporter genes, which results in the activation of ZIP1 in shoots, reduction of ZIP2 transcript levels in roots, and enhanced expression of IRT2 in roots. These data support the conclusion that IRT1 is an essential metal transporter required for proper development and regulation of iron and zinc homeostasis in Arabidopsis.

Direct and general support maintenance manual for truck, tractor, line haul, 52,000 GVWR, 6 x 4, M915A2 (NSN 2320-01-272-5029), truck, tractor, light equipment transporter (LET), 68,000 GVWR, 6 x 6 w/winch, M916A1 (NSN 2320-01-272-5028).

"June 1992."

Unit maintenance manual for truck, tractor, line haul, 52,000 GVWR, 6 x 4, M915A2 (NSN 2320-01-272-5029), truck, tractor, light equipment transporter (LET), 68,000 GVWR, 6 x 6 w/winch, M916A1 (NSN 2320-01-272-5028).

"June 1992."

Organizational maintenance repair parts and special tools list for loader-transporter, guided missile, M688A1 1450-01-133-4439 handling unit, guided missile equipment M39 1450-01-132-7715 hoisting unit, tripod M38 1450-00-937-0893 sling, beam type M22 1450-00-937-0894, Lance Field Artillery Missile System.

Includes index.

Direct support and general support maintenance repair parts and special tools list including depot maintenance repair parts and special tools for loader-transporter, guided missile, M688A1, 1450-01-133-4439, handling unit, guided missile equipment, M39, 1450-01-132-7715, hoisting unit, tripod, M38, 1450-00-937-0893, sling, beam type, M22, 1450-00-937-0894, Lance Field Artillery Missile System.

Includes index.

Operator and organizational maintenance manual, loader transporter M688, mobility kit M234, tripod hoist M38, sling beam M22, Lance Missile System.

"MS 419586."

Direct support and general support maintenance manual : loader-transporter, guided missile, XM501E3 (Hawk guided missile system), part number 11675300, NSN 1450-00-066-8873.

Includes index.

Operator's manual : loader-transporter, guided missile, XM501E3 (Hawk guided missile system) (1450-00-066-8873).

"March 1988."

Organizational maintenance manual : loader-transporter, guided missile, XM501E3 (Hawk guided missile system), part number 11675300, NSN 1450-00-066-8873).

"June 1979."

Operator's manual : truck tractor, commercial heavy equipment transporter (C-HET), 85,000 GVWR, 8 x 6, M911, (NSN 2320-01-025-3733).

Includes index.

Organizational maintenance repair parts and special tools lists : truck, tractor, commercial, heavy equipment transporter, C-HET, 85,000 GVWR, 8x6, Army model M911, NSN 2320-01-025-3733.

Includes index.