Secondary structure and orientation of the surfactant protein SP-B in a lipid environment. A Fourier transform infrared spectroscopy study

Vandenbussche, Guy; Clercx, Anne; Clercx, Michel; Curstedt, Tore; Johansson, Jan; Jörnvall, Hans; Ruysschaert, Jean Marie

doi:10.1021/bi00153a008

Cited by 146 publications

(125 citation statements)

References 67 publications

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“…This may facilitate specific interactions of SP-B with anionic phospholipids as well as zwitterionic phosphatidylcholines in lung surfactants. Due to its overall amphipathic structure, SP-B likely occupies a relatively peripheral position in phospholipid bilayers where it can interact with both head groups and hydrophobic chains (1,10,40,42,43,53). SP-B can order the head-group region of lipid bilayers and increase the gel-to-liquid crystal transition temperatures of fluid phospholipids (1,2,30,53,54).…”

Section: Discussionmentioning

confidence: 99%

“…Due to its overall amphipathic structure, SP-B likely occupies a relatively peripheral position in phospholipid bilayers where it can interact with both head groups and hydrophobic chains (1,10,40,42,43,53). SP-B can order the head-group region of lipid bilayers and increase the gel-to-liquid crystal transition temperatures of fluid phospholipids (1,2,30,53,54). SP-B also broadens phase transition width, indicating an ability to disrupt or reduce order in at least a portion of the bilayer (1,2,23,24,30,43).…”

Section: Discussionmentioning

confidence: 99%

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Content-dependent activity of lung surfactant protein B in mixtures with lipids

Wang

Baatz

Holm

et al. 2002

American Journal of Physiology-Lung Cellular and Molecular Phys

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The content-dependent activity of surfactant protein (SP)-B was studied in mixtures with dipalmitoyl phosphatidylcholine (DPPC), synthetic lipids (SL), and purified phospholipids (PPL) from calf lung surfactant extract (CLSE). At fixed SP-B content, adsorption and dynamic surface tension lowering were ordered as PPL/SP-B ≈ SL/SP-B > DPPC/SP-B. All mixtures were similar in having increased surface activity as SP-B content was incrementally raised from 0.05 to 0.75% by weight. SP-B had small but measurable effects on interfacial properties even at very low levels ≤0.1% by weight. PPL/SP-B (0.75%) had the highest adsorption and dynamic surface activity, approaching the behavior of CLSE. All mixtures containing 0.75% SP-B reached minimum surface tensions <1 mN/m in pulsating bubble studies at low phospholipid concentration (1 mg/ml). Mixtures of PPL or SL with SP-B (0.5%) also had minimum surface tensions <1 mN/m at 1 mg/ml, whereas DPPC/SP-B (0.5%) reached <1 mN/m at 2.5 mg/ml. Physiological activity also was strongly dependent on SP-B content. The ability of instilled SL/SP-B mixtures to improve surfactant-deficient pressure-volume mechanics in excised lavaged rat lungs increased as SP-B content was raised from 0.1 to 0.75% by weight. This study emphasizes the crucial functional activity of SP-B in lung surfactants. Significant differences in SP-B content between exogenous surfactants used to treat respiratory disease could be associated with substantial activity variations.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Content-dependent activity of lung surfactant protein B in mixtures with lipids

Wang

Baatz

Holm

et al. 2002

American Journal of Physiology-Lung Cellular and Molecular Phys

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“…The FTIR spectrum of KL4 in DPPC/PG 7:3 (w/w) bilayers shows a peak maximum at 1656 cm -1, in the spectral region associated with helical structure. Deconvolution and curve fitting between 1700 cm -1 and 1600 cm -1 [8,12,23] yields 84% of a-helices for lipid-associated KL4. KL4 is helical also in non-lipid environments; in trifluoroethanol it gives a CD spectrum which is similar to that obtained in DPC micelles, and FTIR spectroscopy of KL4 alone, i.e.…”

Section: Secondary Structure Of Kl4 In Phospholipid Micellesmentioning

confidence: 99%

“…This film is responsible for lowering the alveolar surface tension, thus preventing lung collapse at end-*Corresponding author. Fax: (46) (8) 337462. E-mail: jan.johansson@mbb.ki.se Abbreviations: ATR, attenuated total reflection; CD, circular dichroism; DPC, dodecylphosphocholine; DPPC, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine; FTIR, Fourier transform infrared; PG, phosphatidylglycerol; TFA, trifluoroacetic acid.…”

Section: Introductionmentioning

confidence: 99%

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The 21‐residue surfactant peptide (LysLeu₄)₄Lys(KL₄) is a transmembrane α‐helix with a mixed nonpolar/polar surface

et al. 1996

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The 21-residue peptide KLLLLKLLLLKLL-LLKLLLLK (KL4) has been synthesized and analyzed regarding its secondary structure and orientation in lipid environments. Fourier transform infrared and circular dichroism spectroscopy shows that the peptide exhibits approximately 80% a-helical content both in dodecylphosphocholine micelles and in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)/phosphatidylglycerol (PG) 7:3 (w/w) bilayers. The positively charged lysine residues are evenly distributed over the entire, otherwise nonpolar, circumference of the helix. This is in sharp contrast to the uneven distribution of polar and nonpolar residues in amphipathic helices. Fourier transform infrared spectroscopy of the peptide inserted in DPPC/PG bilayers shows that the helical axis is oriented parallel to the lipid acyl chains. These data do not support a previous hypothesis that the KL4 peptide interacts with peripheral parts of a phospholipid monolayer and mimics the pulmonary surfactant protein SP-B, which is composed of several amphipathic ¢x-helices. KL4 accelerates the spreading of phospholipid mixtures at an air/water interface but does so less efficiently than other transmembranous helical polypeptides studied.

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Structure and Function of Pulmonary Surfactant Proteins

García‐Álvarez

Alonso

Pérez‐Gil

2019

Encyclopedia of Life Sciences

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Pulmonary surfactant is a lipid/protein complex essential to keep the airspaces of mammalian lungs open. It forms surface‐active films at the respiratory air–liquid interface, reducing surface tension to a minimum and thus minimising the work of breathing. At the same time, surfactant establishes the first barrier against the entry of potential pathogens through the large surface that lungs expose to environment. Both the interfacial and the innate defence activities depend critically on the presence of highly specialised evolutionarily conserved surfactant‐associated proteins. The structure and molecular mechanisms of these proteins have been extensively characterised in the last decades, in studies that constitute the basis for current models on surfactant mechanisms at the alveolar spaces, in health and disease. This article summarises the current knowledge on the structure–function relationships defining the molecular action of pulmonary surfactant proteins and how they are being key actors to maintain operative breathing in the lungs. Key Concepts The presence of specific proteins is essential for pulmonary surfactant to play its crucial role in stabilising the respiratory air–liquid interface. Collectin proteins SP‐A and SP‐D oligomerise to form trimers and supratrimeric oligomers with multivalent binding capacities to sugars and lipids and participate in innate defence mechanisms, binding to the surface of pathogens and allergens to facilitate their clearance. Surfactant protein SP‐B is essential for life; its absence is associated with an irreversible respiratory failure at birth. SP‐B belongs to the saposin protein family and assembles as ring‐shaped oligomers that enclose hydrophobic channels competent to transfer phospholipids between membranes and between membranes and the interface, avoiding its exposure to aqueous environments. Some synthetic peptides designed to mimic key SP‐B motifs are being used to produce alternative surfactant preparations for therapeutic applications. Protein SP‐C is a very hydrophobic helical protein whose expression is linked to the differentiation of lung tissue. Its oligomerisation is associated with surfactant membrane fragmentation and their interconversions at the alveolar spaces.

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Secondary structure and orientation of the surfactant protein SP-B in a lipid environment. A Fourier transform infrared spectroscopy study

Cited by 146 publications

References 67 publications

Content-dependent activity of lung surfactant protein B in mixtures with lipids

Content-dependent activity of lung surfactant protein B in mixtures with lipids

The 21‐residue surfactant peptide (LysLeu₄)₄Lys(KL₄) is a transmembrane α‐helix with a mixed nonpolar/polar surface

Structure and Function of Pulmonary Surfactant Proteins

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Secondary structure and orientation of the surfactant protein SP-B in a lipid environment. A Fourier transform infrared spectroscopy study

Cited by 146 publications

References 67 publications

Content-dependent activity of lung surfactant protein B in mixtures with lipids

Content-dependent activity of lung surfactant protein B in mixtures with lipids

The 21‐residue surfactant peptide (LysLeu4)4Lys(KL4) is a transmembrane α‐helix with a mixed nonpolar/polar surface

Structure and Function of Pulmonary Surfactant Proteins

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The 21‐residue surfactant peptide (LysLeu₄)₄Lys(KL₄) is a transmembrane α‐helix with a mixed nonpolar/polar surface