Recombinant Salmonella arizonae Spermidine export protein MdtI (mdtI)
Description
Functional Role in Polyamine Homeostasis
MdtI partners with MdtJ to form a heterodimeric efflux pump belonging to the small multidrug resistance (SMR) family. This complex mediates spermidine excretion, preventing toxicity from overaccumulation:
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Mechanism:
Experimental Evidence:
A. Polyamine Regulation
MdtI is essential for studying bacterial polyamine metabolism, particularly in:
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Pathogen Survival: Maintains homeostasis in pathogens like Salmonella arizonae, enabling adaptation to host environments .
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Toxin Resistance: Overexpression enhances tolerance to polyamine toxicity, relevant for antibiotic resistance studies .
B. Biotechnological Applications
The MdtJI complex has been engineered for:
Product Specs
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Target Background
KEGG: ses:SARI_01495
STRING: 882884.SARI_01495
Q&A
Basic Research Questions
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How does the MdtI protein sequence differ between Salmonella species?
Comparison of MdtI sequences from different Salmonella species reveals subtle but potentially significant variations. For example:
Species UniProt ID Key Sequence Differences S. arizonae A9MRT8 MQQFEWVHGAWLALAIILEIAANVLLKFSD... S. typhimurium Q7CQK0 MQQFEWIHGAWLGLAIMLEIAANVLLKFSD... Notable differences include the V→I substitution at position 5 and L→G substitution at position 9, which might affect protein folding or spermidine interaction . These variations reflect the evolutionary divergence between Salmonella subspecies and may contribute to functional differences in spermidine export efficiency or substrate specificity .
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What expression systems are most effective for producing recombinant MdtI?
E. coli is the predominant expression system for recombinant MdtI production due to high yield and relatively short turnaround times. The typical methodology involves:
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Cloning the full-length mdtI gene into an expression vector with an N-terminal His-tag
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Expression in E. coli under appropriate induction conditions
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Purification using affinity chromatography
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Storage as a lyophilized powder in Tris/PBS-based buffer with 6% trehalose at pH 8.0
Alternative expression systems include yeast, insect cells with baculovirus, and mammalian cells, with the latter two providing posttranslational modifications that may be necessary for certain functional studies . The choice depends on research goals, with E. coli being optimal for structural studies and mammalian systems potentially better for functional assays requiring proper folding.
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