An ABC-type, high-affinity urea permease identified in cyanobacteria

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Urea is a crucial nitrogen source for microorganisms.
• Molecular mechanisms of bacterial urea active transporters remain largely uncharacterized.
• Cyanobacteria like Synechocystis and Anabaena utilize urea but lack identified transport systems.

Purpose of the Study:

• To identify and characterize the molecular components of high-affinity urea active transporters in cyanobacteria.
• To elucidate the genetic basis and regulation of urea uptake in Synechocystis and Anabaena.
• To determine if urea is a substrate for ABC-type transporters in bacteria.

Main Methods:

• Uptake assays using [14C]-urea in wild-type and mutant strains of Synechocystis and Anabaena.
• Genetic analysis involving gene inactivation and identification of open reading frames (ORFs).
• Transcriptional analysis to study gene expression and promoter identification.

Main Results:

• Synechocystis and Anabaena exhibit high-affinity urea uptake, regulated by nitrogen availability.
• A specific ORF, sll0374 in Synechocystis and urtE in Anabaena, is essential for urea transport.
• The Anabaena urtABCDE gene cluster encodes a functional ABC-type urea permease, regulated by the NtcA transcription factor.

Conclusions:

• The study identifies a novel ABC-type transporter system responsible for active urea uptake in cyanobacteria.
• This discovery expands the known substrate range of ABC-type transporters.
• The findings suggest a significant role for this transporter in bacterial urea scavenging in natural environments.