Characterization and implications of the cell surface reactivity of Calothrix sp. strain KC97

V. R. Phoenix, R. E. Martinez, K. O. Konhauser, F. G. Ferris

Research output: Contribution to journalArticle

86 Citations (Scopus)

Abstract

The cell surface reactivity of the cyanobacterium Calothrix sp. strain KC97, an isolate from the Krisuvik hot spring, Iceland, was investigated in terms of its proton binding behavior and charge characteristics by using acid-base titrations, electrophoretic mobility analysis, and transmission electron microscopy. Analysis of titration data with the linear programming optimization method showed that intact filaments were dominated by surface proton binding sites inferred to be carboxyl groups (acid dissociation constants [pK a] between 5.0 and 6.2) and amine groups (mean pK a of 8.9). Sheath material isolated by using lysozyme and sodium dodecyl sulfate generated pK a spectra similarly dominated by carboxyls (pK a of 4.6 to 6.1) and amines (pK a of 8.1 to 9.2). In both intact filaments and isolated sheath material, the lower ligand concentrations at mid-pK a values were ascribed to phosphoryl groups. Whole filaments and isolated sheath material displayed total reactive-site densities of 80.3 × 10 -5 and 12.3 × 10 -5 mol/g (dry mass) of cyanobacteria, respectively, implying that much of the surface reactivity of this microorganism is located on the cell wall and not the sheath. This is corroborated by electrophoretic mobility measurements that showed that the sheath has a net neutral charge at mid-pHs. In contrast, unsheathed cells exhibited a stronger negative-charge characteristic. Additionally, transmission electron microscopy analysis of ultrathin sections stained with heavy metals further demonstrated that most of the reactive binding sites are located upon the cell wall. Thus, the cell surface reactivity of Calothrix sp. strain KC97 can be described as a dual layer composed of a highly reactive cell wall enclosed within a poorly reactive sheath.

LanguageEnglish
Pages4827-4834
Number of pages8
JournalApplied and Environmental Microbiology
Volume68
Issue number10
DOIs
Publication statusPublished - 31 Oct 2002
Externally publishedYes

Fingerprint

Calothrix
charge characteristics
Cell Wall
cell walls
Cyanobacteria
titration
Transmission Electron Microscopy
amines
protons
Amines
transmission electron microscopy
Protons
binding sites
Catalytic Domain
Binding Sites
Hot Springs
Linear Programming
Iceland
cyanobacterium
hot springs

Keywords

  • transmission electron microscopy
  • electrophoresis
  • enzymes
  • heavy metals
  • optimisation

Cite this

Phoenix, V. R. ; Martinez, R. E. ; Konhauser, K. O. ; Ferris, F. G. / Characterization and implications of the cell surface reactivity of Calothrix sp. strain KC97. In: Applied and Environmental Microbiology. 2002 ; Vol. 68, No. 10. pp. 4827-4834.
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Characterization and implications of the cell surface reactivity of Calothrix sp. strain KC97. / Phoenix, V. R.; Martinez, R. E.; Konhauser, K. O.; Ferris, F. G.

In: Applied and Environmental Microbiology, Vol. 68, No. 10, 31.10.2002, p. 4827-4834.

Research output: Contribution to journalArticle

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T1 - Characterization and implications of the cell surface reactivity of Calothrix sp. strain KC97

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AU - Martinez, R. E.

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N2 - The cell surface reactivity of the cyanobacterium Calothrix sp. strain KC97, an isolate from the Krisuvik hot spring, Iceland, was investigated in terms of its proton binding behavior and charge characteristics by using acid-base titrations, electrophoretic mobility analysis, and transmission electron microscopy. Analysis of titration data with the linear programming optimization method showed that intact filaments were dominated by surface proton binding sites inferred to be carboxyl groups (acid dissociation constants [pK a] between 5.0 and 6.2) and amine groups (mean pK a of 8.9). Sheath material isolated by using lysozyme and sodium dodecyl sulfate generated pK a spectra similarly dominated by carboxyls (pK a of 4.6 to 6.1) and amines (pK a of 8.1 to 9.2). In both intact filaments and isolated sheath material, the lower ligand concentrations at mid-pK a values were ascribed to phosphoryl groups. Whole filaments and isolated sheath material displayed total reactive-site densities of 80.3 × 10 -5 and 12.3 × 10 -5 mol/g (dry mass) of cyanobacteria, respectively, implying that much of the surface reactivity of this microorganism is located on the cell wall and not the sheath. This is corroborated by electrophoretic mobility measurements that showed that the sheath has a net neutral charge at mid-pHs. In contrast, unsheathed cells exhibited a stronger negative-charge characteristic. Additionally, transmission electron microscopy analysis of ultrathin sections stained with heavy metals further demonstrated that most of the reactive binding sites are located upon the cell wall. Thus, the cell surface reactivity of Calothrix sp. strain KC97 can be described as a dual layer composed of a highly reactive cell wall enclosed within a poorly reactive sheath.

AB - The cell surface reactivity of the cyanobacterium Calothrix sp. strain KC97, an isolate from the Krisuvik hot spring, Iceland, was investigated in terms of its proton binding behavior and charge characteristics by using acid-base titrations, electrophoretic mobility analysis, and transmission electron microscopy. Analysis of titration data with the linear programming optimization method showed that intact filaments were dominated by surface proton binding sites inferred to be carboxyl groups (acid dissociation constants [pK a] between 5.0 and 6.2) and amine groups (mean pK a of 8.9). Sheath material isolated by using lysozyme and sodium dodecyl sulfate generated pK a spectra similarly dominated by carboxyls (pK a of 4.6 to 6.1) and amines (pK a of 8.1 to 9.2). In both intact filaments and isolated sheath material, the lower ligand concentrations at mid-pK a values were ascribed to phosphoryl groups. Whole filaments and isolated sheath material displayed total reactive-site densities of 80.3 × 10 -5 and 12.3 × 10 -5 mol/g (dry mass) of cyanobacteria, respectively, implying that much of the surface reactivity of this microorganism is located on the cell wall and not the sheath. This is corroborated by electrophoretic mobility measurements that showed that the sheath has a net neutral charge at mid-pHs. In contrast, unsheathed cells exhibited a stronger negative-charge characteristic. Additionally, transmission electron microscopy analysis of ultrathin sections stained with heavy metals further demonstrated that most of the reactive binding sites are located upon the cell wall. Thus, the cell surface reactivity of Calothrix sp. strain KC97 can be described as a dual layer composed of a highly reactive cell wall enclosed within a poorly reactive sheath.

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