Disease relevance of hupL

• Heterocyst-specific excision of the Anabaena sp. strain PCC 7120 hupL element requires xisC [1].
• Expression of xisC in Escherichia coli was sufficient to produce rearrangement of an artificial substrate plasmid bearing the hupL element recombination sites [1].
• From partial libraries of genomic DNA, two clones (pNfo01 and pNfo02) were selected and sequenced, revealing the complete sequence of both a hupS (960 bases) and a hupL (1,593 bases) homologue in Nostoc sp. strain PCC 73102 [2].

High impact information on hupL

• An open reading frame, named xisC, identified near one end of the hupL DNA element is presumed to encode the element's site-specific recombinase [3].
• Late during heterocyst differentiation, a 10.5-kb DNA element is excised from within the hupL gene by site-specific recombination between 16-bp direct repeats that flank the element [3].
• Programmed DNA rearrangement of a cyanobacterial hupL gene in heterocysts [3].
• The predicted HupL polypeptide is homologous to the large subunit of [NiFe] uptake hydrogenases. hupL is expressed similarly to the nitrogen-fixation genes; hupL message was detected only during the late stages of heterocyst development [3].
• The DNA elements are named after the genes that they interrupt: nifD, fdxN, and hupL [1].

Biological context of hupL

• Overexpression of xisC from a plasmid in a wild-type background caused a low level of hupL rearrangement even in nitrogen-replete conditions [1].
• Gene expression analyses show that these hyp genes are, like hupL, transcribed under N(2)-fixing but not under non-N(2)-fixing growth conditions [4].

Regulatory relationships of hupL

• A strain in which the xisC gene was inactivated showed no detectable excision of the hupL element. hupL encodes the large subunit of uptake hydrogenase [1].

Other interactions of hupL

• H(2) production by the hupL(-)/ hoxH(-) mutant was slightly lower than, but almost equal to, that of the hupL(-) mutant [5].
• In contrast to the hupL gene of Anabaena sp. strain PCC 7120, which is interrupted by a 10.5-kb DNA fragment in vegetative cells, there is no programmed rearrangement within the hupL gene during the heterocyst differentiation of A. variabilis [6].

Analytical, diagnostic and therapeutic context of hupL

• As shown by RT-PCR, hupS and hupL constitute a single transcript in Nostoc sp. PCC 73102 [7].

References