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Gene Review

hupL  -  [NiFe] uptake hydrogenase large subunit

Nostoc sp. PCC 7120


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



  1. Heterocyst-specific excision of the Anabaena sp. strain PCC 7120 hupL element requires xisC. Carrasco, C.D., Holliday, S.D., Hansel, A., Lindblad, P., Golden, J.W. J. Bacteriol. (2005) [Pubmed]
  2. Hydrogen uptake in Nostoc sp. strain PCC 73102. Cloning and characterization of a hupSL homologue. Oxelfelt, F., Tamagnini, P., Lindblad, P. Arch. Microbiol. (1998) [Pubmed]
  3. Programmed DNA rearrangement of a cyanobacterial hupL gene in heterocysts. Carrasco, C.D., Buettner, J.A., Golden, J.W. Proc. Natl. Acad. Sci. U.S.A. (1995) [Pubmed]
  4. Cloning and characterisation of a hyp gene cluster in the filamentous cyanobacterium Nostoc sp. strain PCC 73102. Hansel, A., Axelsson, R., Lindberg, P., Troshina, O.Y., Wünschiers, R., Lindblad, P. FEMS Microbiol. Lett. (2001) [Pubmed]
  5. Disruption of the uptake hydrogenase gene, but not of the bidirectional hydrogenase gene, leads to enhanced photobiological hydrogen production by the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120. Masukawa, H., Mochimaru, M., Sakurai, H. Appl. Microbiol. Biotechnol. (2002) [Pubmed]
  6. Transcriptional and mutational analysis of the uptake hydrogenase of the filamentous cyanobacterium Anabaena variabilis ATCC 29413. Happe, T., Schütz, K., Böhme, H. J. Bacteriol. (2000) [Pubmed]
  7. hupS and hupL constitute a transcription unit in the cyanobacterium Nostoc sp. PCC 73102. Lindberg, P., Hansel, A., Lindblad, P. Arch. Microbiol. (2000) [Pubmed]
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