Hemoglobin in
            <i>Frankia</i>
            , a Nitrogen-Fixing Actinomycete

Tjepkema, John D.; Cashon, Robert E.; Beckwith, Jason; Schwintzer, Christa R.

doi:10.1128/aem.68.5.2629-2631.2002

Cited by 24 publications

(16 citation statements)

References 26 publications

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“…We hypothesized that Frankia trHbO may deliver oxygen to terminal oxidases to stimulate their rates of respiration under hypoxic conditions. Consistent with this model, Tjepkema et al (26) observed rapid oxygen kinetics (oxygen association and oxygen disassociation rates, kЈ on and k off ) for Frankia hemoglobin, suggesting the role of oxygen transport over short distances. In M. tuberculosis, trHbO has been shown to function as an oxygen shuttle to respiratory enzymes (10,12,18).…”

supporting

confidence: 49%

“…Hemoglobin production seems to be widespread among all of the Frankia isolates (3,26), but its specific function(s) is unknown. Biochemical studies have shown that the presence or absence of a combined nitrogen source does not affect total hemoglobin production (3), but total hemoglobin levels are greater when cells are grown with 2% oxygen than when they are grown with 20% oxygen.…”

mentioning

confidence: 99%

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Nitric Oxide and Oxygen Regulate Truncated Hemoglobin Gene Expression inFrankiaStrain CcI3

Niemann

Tisa

2008

J Bacteriol

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The Frankia genome contains two truncated hemoglobin genes (hboN and hboO) whose functions remain to be determined. Nitric oxide (NO) generated by the addition of 400 M SNAP (S-nitroso-N-acetylpenicillamine) caused a 10-fold increase in hboN gene expression but had no effect on hboO expression. The addition of the NO scavenger, carboxy-PT10, reduced the effect of SNAP. hboO gene expression increased under low-oxygen conditions, while hboN expression was unaffected. These results suggest that HboN may function in protection from nitrosative stress and that HboO may act as an oxygen transport molecule for increased respiration in hypoxic environments.

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supporting

confidence: 49%

mentioning

confidence: 99%

Nitric Oxide and Oxygen Regulate Truncated Hemoglobin Gene Expression inFrankiaStrain CcI3

Niemann

Tisa

2008

J Bacteriol

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“…It was therefore expected, that the hemoglobin cloned in this study encoded the major fraction of M. gale nodule hemoglobin. It has been suggested that the minor monomeric fraction has a microbial genetic origin (Tjepkema et al 2002). This minor monomer would represent a truncated hemoglobin (2-on-2 hemoglobin) which has not only been shown to be present in bacteria, but also to be present in plants ) and have been found in legume nodules (Vieweg et al 2005).…”

Section: Discussionmentioning

confidence: 99%

A single hemoglobin gene in Myrica gale retains both symbiotic and non-symbiotic specificity

Heckmann

Hebelstrup

Larsen³

et al. 2006

Plant Mol Biol

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Here, a hemoglobin gene from the nitrogen-fixing actinorhizal plant Myrica gale was isolated, cloned and sequenced. The gene (MgHb) was a class I hemoglobin with strong sequence homology to non-symbiotic hemoglobin genes. MgHb is highly expressed in symbiotic root nodules, but transcripts and protein were also detected in leaves of M. gale. In Arabidopsis thaliana the MgHb promoter, linked to a beta-glucuronidase coding region, directed expression in the vascular tissue, in shoot meristem and at root branch point--a pattern very similar to the combined expression pattern of the two non-symbiotic A. thaliana hemoglobin promoters AHb1 and AHb2. The results points to a symbiotic as well as a non-symbiotic specificity of MgHb similar to a hemoglobin gene identified in Parasponia andersonii, but different from the situation in Casuarina glauca--a close actinorhizal relative of M. gale.

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“…Each time point has two independent replicates from a single field of view. Error bars represent standard deviation proposed to provide O 2 protection for nitrogenase (Murry et al 1985;Berg and McDowell 1988;Tjepkema et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Growth and development of Frankia spp. strain CcI3 at the single-hypha level in liquid culture

Huang

Benson

2011

Arch Microbiol

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Filamentous actinobacteria from the genus Frankia grow by hyphal tip extension and branching. The growth kinetics and branching pattern of Frankia are not well studied, especially at the early stages of mycelial development. Here, we compare the growth of Frankia sp. strain CcI3 in liquid cultures with and without proteose peptone #3 (PP3) using time-lapse photomicrography and image analysis. Individual hyphae showed a pseudolinear increase in length at early stages of development, whereas at the mycelial level, the aggregate length of hyphae described an exponential rate before slowing. Growth based on optical density or microscopic observations was similar in medium with or without PP3. However, PP3 altered the pattern of mycelial development by increasing branching. Distances between the hyphal apex and first branches were on average shorter in PP3-containing media. The final interbranch distances were also shorter in PP3 medium indicating that hyphae tended to branch earlier and more often when supplemented with PP3 to give a more compact mycelium. Vesicle development in nitrogen-fixing cultures limited cell expansion as a result of vesicles truncating growth on new branches. The results provide some explanation for the growth kinetics of Frankia and some indication of how growth rates may be improved.

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Hemoglobin in Frankia , a Nitrogen-Fixing Actinomycete

Cited by 24 publications

References 26 publications

Nitric Oxide and Oxygen Regulate Truncated Hemoglobin Gene Expression inFrankiaStrain CcI3

Nitric Oxide and Oxygen Regulate Truncated Hemoglobin Gene Expression inFrankiaStrain CcI3

A single hemoglobin gene in Myrica gale retains both symbiotic and non-symbiotic specificity

Growth and development of Frankia spp. strain CcI3 at the single-hypha level in liquid culture

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